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<button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Casadio%2C+C&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Casadio%2C+C&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Casadio%2C+C&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> </ul> </nav> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2501.08574">arXiv:2501.08574</a> <span> [<a href="https://arxiv.org/pdf/2501.08574">pdf</a>, <a href="https://arxiv.org/format/2501.08574">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202450003">10.1051/0004-6361/202450003 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Gamma-ray flares from the jet of the blazar CTA 102 in 2016-2018 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kim%2C+S">Sanghyun Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Lee%2C+S">Sang-Sung Lee</a>, <a href="/search/astro-ph?searchtype=author&query=Algaba%2C+J+C">Juan Carlos Algaba</a>, <a href="/search/astro-ph?searchtype=author&query=Rani%2C+B">Bindu Rani</a>, <a href="/search/astro-ph?searchtype=author&query=Park%2C+J">Jongho Park</a>, <a href="/search/astro-ph?searchtype=author&query=Jeong%2C+H">Hyeon-Woo Jeong</a>, <a href="/search/astro-ph?searchtype=author&query=Cheong%2C+W+Y">Whee Yeon Cheong</a>, <a href="/search/astro-ph?searchtype=author&query=D%27Ammando%2C+F">Filippo D'Ammando</a>, <a href="/search/astro-ph?searchtype=author&query=L%C3%A4hteenm%C3%A4ki%2C+A">Anne L盲hteenm盲ki</a>, <a href="/search/astro-ph?searchtype=author&query=Tornikoski%2C+M">Merja Tornikoski</a>, <a href="/search/astro-ph?searchtype=author&query=Tammi%2C+J">Joni Tammi</a>, <a href="/search/astro-ph?searchtype=author&query=Ramakrishnan%2C+V">Venkatessh Ramakrishnan</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">Carolina Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Escudero%2C+J">Juan Escudero</a>, <a href="/search/astro-ph?searchtype=author&query=Fuentes%2C+A">Antonio Fuentes</a>, <a href="/search/astro-ph?searchtype=author&query=Traianou%2C+E">Efthalia Traianou</a>, <a href="/search/astro-ph?searchtype=author&query=Myserlis%2C+I">Ioannis Myserlis</a>, <a href="/search/astro-ph?searchtype=author&query=Thum%2C+C">Clemens Thum</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2501.08574v1-abstract-short" style="display: inline;"> CTA 102 is a $纬$-ray bright blazar that exhibited multiple flares in observations by the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope during the period of 2016-2018. We present results from the analysis of multi-wavelength light curves aiming at revealing the nature of $纬$-ray flares from the relativistic jet in the blazar. We analyse radio, optical, X-ray, and $纬$-ray data ob… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.08574v1-abstract-full').style.display = 'inline'; document.getElementById('2501.08574v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.08574v1-abstract-full" style="display: none;"> CTA 102 is a $纬$-ray bright blazar that exhibited multiple flares in observations by the Large Area Telescope on board the Fermi Gamma-Ray Space Telescope during the period of 2016-2018. We present results from the analysis of multi-wavelength light curves aiming at revealing the nature of $纬$-ray flares from the relativistic jet in the blazar. We analyse radio, optical, X-ray, and $纬$-ray data obtained in a period from 2012 September 29 to 2018 October 8. We identify six flares in the $纬$-ray light curve, showing a harder-when-brighter-trend in the $纬$-ray spectra. We perform a cross-correlation analysis of the multi-wavelength light curves. We find nearly zero time lags between the $纬$-ray and optical and X-ray light curves, implying a common spatial origin for the emission in these bands. We find significant correlations between the $纬$-ray and radio light curves as well as negative/positive time lags with the $纬$-ray emission lagging/leading the radio during different flaring periods. The time lags between $纬$-ray and radio emission propose the presence of multiple $纬$-ray emission sites in the source. As seen in 43 GHz images from the Very Long Baseline Array, two moving disturbances (or shocks) were newly ejected from the radio core. The $纬$-ray flares from 2016 to 2017 are temporally coincident with the interaction between a traveling shock and a quasi-stationary one at $\sim$0.1 mas from the core. The other shock is found to emerge from the core nearly simultaneous with the $纬$-ray flare in 2018. Our results suggest that the $纬$-ray flares originated from shock-shock interactions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.08574v1-abstract-full').style.display = 'none'; document.getElementById('2501.08574v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 January, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2025. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">14 pages, 15 figures, 4 tables, accepted for publication in A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 694, A291 (2025) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.22319">arXiv:2410.22319</a> <span> [<a href="https://arxiv.org/pdf/2410.22319">pdf</a>, <a href="https://arxiv.org/format/2410.22319">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202452311">10.1051/0004-6361/202452311 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A wiggling filamentary jet at the origin of the blazar multi-wavelength behaviour </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Raiteri%2C+C+M">C. M. Raiteri</a>, <a href="/search/astro-ph?searchtype=author&query=Villata%2C+M">M. Villata</a>, <a href="/search/astro-ph?searchtype=author&query=Carnerero%2C+M+I">M. I. Carnerero</a>, <a href="/search/astro-ph?searchtype=author&query=Kurtanidze%2C+S+O">S. O. Kurtanidze</a>, <a href="/search/astro-ph?searchtype=author&query=Mirzaqulov%2C+D+O">D. O. Mirzaqulov</a>, <a href="/search/astro-ph?searchtype=author&query=Ben%C3%ADtez%2C+E">E. Ben铆tez</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">G. Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Carosati%2C+D">D. Carosati</a>, <a href="/search/astro-ph?searchtype=author&query=Acosta-Pulido%2C+J+A">J. A. Acosta-Pulido</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">I. Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Andreeva%2C+T+S">T. S. Andreeva</a>, <a href="/search/astro-ph?searchtype=author&query=Apolonio%2C+G">G. Apolonio</a>, <a href="/search/astro-ph?searchtype=author&query=Bachev%2C+R">R. Bachev</a>, <a href="/search/astro-ph?searchtype=author&query=Borman%2C+G+A">G. A. Borman</a>, <a href="/search/astro-ph?searchtype=author&query=Bozhilov%2C+V">V. Bozhilov</a>, <a href="/search/astro-ph?searchtype=author&query=Brown%2C+L+F">L. F. Brown</a>, <a href="/search/astro-ph?searchtype=author&query=Carbonell%2C+W">W. Carbonell</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">C. Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+W+P">W. P. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Damljanovic%2C+G">G. Damljanovic</a>, <a href="/search/astro-ph?searchtype=author&query=Ehgamberdiev%2C+S+A">S. A. Ehgamberdiev</a>, <a href="/search/astro-ph?searchtype=author&query=Elsaesser%2C+D">D. Elsaesser</a>, <a href="/search/astro-ph?searchtype=author&query=Escudero%2C+J">J. Escudero</a>, <a href="/search/astro-ph?searchtype=author&query=Feige%2C+M">M. Feige</a>, <a href="/search/astro-ph?searchtype=author&query=Fuentes%2C+A">A. Fuentes</a> , et al. (74 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.22319v1-abstract-short" style="display: inline;"> Blazars are beamed active galactic nuclei known for their strong multi-wavelength variability on timescales from years down to minutes. We aim to investigate the suitability of the twisting jet model presented in previous works to explain the multi-wavelength behaviour of BL Lacertae, the prototype of one of the blazar classes. According to this model, the jet is inhomogeneous, curved, and twistin… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.22319v1-abstract-full').style.display = 'inline'; document.getElementById('2410.22319v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.22319v1-abstract-full" style="display: none;"> Blazars are beamed active galactic nuclei known for their strong multi-wavelength variability on timescales from years down to minutes. We aim to investigate the suitability of the twisting jet model presented in previous works to explain the multi-wavelength behaviour of BL Lacertae, the prototype of one of the blazar classes. According to this model, the jet is inhomogeneous, curved, and twisting, and the long-term variability is due to changes in the Doppler factor due to variations in the orientation of the jet-emitting regions. We analysed optical data of the source obtained during monitoring campaigns organised by the Whole Earth Blazar Telescope (WEBT) in 2019-2022, together with radio data from the WEBT and other teams, and gamma-ray data from the Fermi satellite. In this period, BL Lacertae underwent an extraordinary activity phase, reaching its historical optical and gamma-ray brightness maxima. The application of the twisting jet model to the source light curves allows us to infer the wiggling motion of the optical, radio, and gamma-ray jet-emitting regions. The optical-radio correlation shows that the changes in the radio viewing angle follow those in the optical viewing angle by about 120 days, and it suggests that the jet is composed of plasma filaments, which is in agreement with some radio high-resolution observations of other sources. The gamma-ray emitting region is found to be co-spatial with the optical one, and the analysis of the gamma-optical correlation is consistent with both the geometric interpretation and a synchrotron self-Compton (SSC) origin of the high-energy photons. We propose a geometric scenario where the jet is made up of a pair of emitting plasma filaments in a sort of double-helix curved rotating structure, whose wiggling motion produces changes in the Doppler beaming and can thus explain the observed multi-wavelength long-term variability. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.22319v1-abstract-full').style.display = 'none'; document.getElementById('2410.22319v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">In press for A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 692 (2024) A48 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2409.15229">arXiv:2409.15229</a> <span> [<a href="https://arxiv.org/pdf/2409.15229">pdf</a>, <a href="https://arxiv.org/format/2409.15229">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202452340">10.1051/0004-6361/202452340 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> SMILE: Discriminating milli-lens systems in a VLBI pilot project </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=P%C3%B6tzl%2C+F+M">F. M. P枚tzl</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">C. Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Kalaitzidakis%2C+G">G. Kalaitzidakis</a>, <a href="/search/astro-ph?searchtype=author&query=%C3%81lvarez-Ortega%2C+D">D. 脕lvarez-Ortega</a>, <a href="/search/astro-ph?searchtype=author&query=Kumar%2C+A">A. Kumar</a>, <a href="/search/astro-ph?searchtype=author&query=Missaglia%2C+V">V. Missaglia</a>, <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D">D. Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Janssen%2C+M">M. Janssen</a>, <a href="/search/astro-ph?searchtype=author&query=Loudas%2C+N">N. Loudas</a>, <a href="/search/astro-ph?searchtype=author&query=Pavlidou%2C+V">V. Pavlidou</a>, <a href="/search/astro-ph?searchtype=author&query=Readhead%2C+A+C+S">A. C. S. Readhead</a>, <a href="/search/astro-ph?searchtype=author&query=Tassis%2C+K">K. Tassis</a>, <a href="/search/astro-ph?searchtype=author&query=Wilkinson%2C+P+N">P. N. Wilkinson</a>, <a href="/search/astro-ph?searchtype=author&query=Zensus%2C+J+A">J. A. Zensus</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2409.15229v3-abstract-short" style="display: inline;"> Dark Matter (DM) remains poorly probed on critical, sub-galactic scales, where predictions from different models diverge in terms of abundance and density profiles of halos. Gravitational lens systems on milli-arcsecond scales (milli-lenses) are expected for a population of dense DM halos (free-floating or sub-halos) and free-floating supermassive black holes in the mass range of $10^6$ to… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.15229v3-abstract-full').style.display = 'inline'; document.getElementById('2409.15229v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2409.15229v3-abstract-full" style="display: none;"> Dark Matter (DM) remains poorly probed on critical, sub-galactic scales, where predictions from different models diverge in terms of abundance and density profiles of halos. Gravitational lens systems on milli-arcsecond scales (milli-lenses) are expected for a population of dense DM halos (free-floating or sub-halos) and free-floating supermassive black holes in the mass range of $10^6$ to $10^9\,M_\odot$. In this paper, we aim to look for milli-lens systems via a systematic search in a large sample of radio-loud AGN observed with very-long-baseline interferometry (VLBI). We present the observational strategy to discriminate milli-lenses from contaminant objects mimicking a milli-lens morphology. In a pilot project, we have investigated VLBI images from 13,828 sources from the Astrogeo VLBI image database and reduced the number of candidates to 40 in a first step. We present here the images and analysis of new sensitive follow-up observations with the EVN at 5 and 22 GHz and streamline our analysis to reject milli-lens candidates. By using constraints such as the surface brightness ratio, conservation of spectral shape, stability of flux ratios over time, and changes in morphology, we can confidently discriminate between milli-lenses and contaminant objects that mimick them. Using the above constraints, we rule out 31 out of our initial 40 candidates of milli-lens systems, demonstrating the power of our approach. Also, we found many new candidate compact symmetric objects, which are thought to be primarily short-lived jetted radio sources. This serves as a pathfinder for the final sample used for the Search for MIlli-LEnses (SMILE) project, which will allow us to constrain DM models by comparing the results to theoretical predictions. This SMILE sample will consist of $\sim$5,000 sources based on the VLA CLASS survey, including many observations obtained for this project specifically. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2409.15229v3-abstract-full').style.display = 'none'; document.getElementById('2409.15229v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 February, 2025; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">43 pages, 41 figures, accepted for publication in Astronomy & Astrophysics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.11128">arXiv:2407.11128</a> <span> [<a href="https://arxiv.org/pdf/2407.11128">pdf</a>, <a href="https://arxiv.org/format/2407.11128">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> </div> <p class="title is-5 mathjax"> X-ray and multiwavelength polarization of Mrk 501 from 2022 to 2023 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Chen%2C+C+J">Chien-Ting J. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Ehlert%2C+S+R">Steven R. Ehlert</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Wu%2C+K">Kinwah Wu</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Mizuno%2C+T">Tsunefumi Mizuno</a>, <a href="/search/astro-ph?searchtype=author&query=Kouch%2C+P+M">Pouya M. Kouch</a>, <a href="/search/astro-ph?searchtype=author&query=Lindfors%2C+E">Elina Lindfors</a>, <a href="/search/astro-ph?searchtype=author&query=Borman%2C+G+A">George A. Borman</a>, <a href="/search/astro-ph?searchtype=author&query=Grishina%2C+T+S">Tatiana S. Grishina</a>, <a href="/search/astro-ph?searchtype=author&query=Kopatskaya%2C+E+N">Evgenia N. Kopatskaya</a>, <a href="/search/astro-ph?searchtype=author&query=Larionova%2C+E+G">Elena G. Larionova</a>, <a href="/search/astro-ph?searchtype=author&query=Morozova%2C+D+A">Daria A. Morozova</a>, <a href="/search/astro-ph?searchtype=author&query=Savchenko%2C+S+S">Sergey S. Savchenko</a>, <a href="/search/astro-ph?searchtype=author&query=Troitsky%2C+I+S">Ivan S. Troitsky</a>, <a href="/search/astro-ph?searchtype=author&query=Troitskaya%2C+Y+V">Yulia V. Troitskaya</a> , et al. (121 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.11128v1-abstract-short" style="display: inline;"> We present multiwavelength polarization measurements of the luminous blazar Mrk~501 over a 14-month period. The 2--8 keV X-ray polarization was measured with the Imaging X-ray Polarimetry Explorer (IXPE) with six 100-ks observations spanning from 2022 March to 2023 April. Each IXPE observation was accompanied by simultaneous X-ray data from NuSTAR, Swift/XRT, and/or XMM-Newton. Complementary optic… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.11128v1-abstract-full').style.display = 'inline'; document.getElementById('2407.11128v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.11128v1-abstract-full" style="display: none;"> We present multiwavelength polarization measurements of the luminous blazar Mrk~501 over a 14-month period. The 2--8 keV X-ray polarization was measured with the Imaging X-ray Polarimetry Explorer (IXPE) with six 100-ks observations spanning from 2022 March to 2023 April. Each IXPE observation was accompanied by simultaneous X-ray data from NuSTAR, Swift/XRT, and/or XMM-Newton. Complementary optical-infrared polarization measurements were also available in the B, V, R, I, and J bands, as were radio polarization measurements from 4.85 GHz to 225.5 GHz. Among the first five IXPE observations, we did not find significant variability in the X-ray polarization degree and angle with IXPE. However, the most recent sixth observation found an elevated polarization degree at $>3蟽$ above the average of the other five observations. The optical and radio measurements show no apparent correlations with the X-ray polarization properties. Throughout the six IXPE observations, the X-ray polarization degree remained higher than, or similar to, the R-band optical polarization degree, which remained higher than the radio value. This is consistent with the energy-stratified shock scenario proposed to explain the first two IXPE observations, in which the polarized X-ray, optical, and radio emission arises from different regions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.11128v1-abstract-full').style.display = 'none'; document.getElementById('2407.11128v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.15554">arXiv:2406.15554</a> <span> [<a href="https://arxiv.org/pdf/2406.15554">pdf</a>, <a href="https://arxiv.org/format/2406.15554">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202451037">10.1051/0004-6361/202451037 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Testing particle acceleration in blazar jets with continuous high-cadence optical polarization observations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Kiehlmann%2C+S">Sebastian Kiehlmann</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+H">Haocheng Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D">Dmitry Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Ben%C3%ADtez%2C+E">Erika Ben铆tez</a>, <a href="/search/astro-ph?searchtype=author&query=Berdyugin%2C+A">Andrei Berdyugin</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">Giacomo Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">Carolina Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+C">Chien-Ting Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+W">Wen-Ping Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Ehlert%2C+S+R">Steven R. Ehlert</a>, <a href="/search/astro-ph?searchtype=author&query=Escudero%2C+J">Juan Escudero</a>, <a href="/search/astro-ph?searchtype=author&query=Grishina%2C+T+S">Tatiana S. Grishina</a>, <a href="/search/astro-ph?searchtype=author&query=Hiriart%2C+D">David Hiriart</a>, <a href="/search/astro-ph?searchtype=author&query=Hsu%2C+A">Angela Hsu</a>, <a href="/search/astro-ph?searchtype=author&query=Imazawa%2C+R">Ryo Imazawa</a>, <a href="/search/astro-ph?searchtype=author&query=Jermak%2C+H+E">Helen E. Jermak</a>, <a href="/search/astro-ph?searchtype=author&query=Jose%2C+J">Jincen Jose</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">Philip Kaaret</a>, <a href="/search/astro-ph?searchtype=author&query=Kopatskaya%2C+E+N">Evgenia N. Kopatskaya</a>, <a href="/search/astro-ph?searchtype=author&query=Lalchand%2C+B">Bhavana Lalchand</a>, <a href="/search/astro-ph?searchtype=author&query=Larionova%2C+E+G">Elena G. Larionova</a> , et al. (22 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2406.15554v1-abstract-short" style="display: inline;"> Variability can be the pathway to understanding the physical processes in astrophysical jets, however, the high-cadence observations required to test particle acceleration models are still missing. Here we report on the first attempt to produce continuous, >24 hour polarization light curves of blazars using telescopes distributed across the globe and the rotation of the Earth to avoid the rising S… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.15554v1-abstract-full').style.display = 'inline'; document.getElementById('2406.15554v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.15554v1-abstract-full" style="display: none;"> Variability can be the pathway to understanding the physical processes in astrophysical jets, however, the high-cadence observations required to test particle acceleration models are still missing. Here we report on the first attempt to produce continuous, >24 hour polarization light curves of blazars using telescopes distributed across the globe and the rotation of the Earth to avoid the rising Sun. Our campaign involved 16 telescopes in Asia, Europe, and North America. We observed BL Lacertae and CGRaBS J0211+1051 for a combined 685 telescope hours. We find large variations in the polarization degree and angle for both sources in sub-hour timescales as well as a ~180 degree rotation of the polarization angle in CGRaBS J0211+1051 in less than two days. We compared our high-cadence observations to Particle-In-Cell magnetic reconnection and turbulent plasma simulations. We find that although the state of the art simulation frameworks can produce a large fraction of the polarization properties, they do not account for the entirety of the observed polarization behavior in blazar jets. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.15554v1-abstract-full').style.display = 'none'; document.getElementById('2406.15554v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">20 pages, 15 figures, 2 tables, accepted for publication in A&A. The data used in the paper are available here: https://doi.org/10.7910/DVN/IETSXS</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 689, A200 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.10141">arXiv:2405.10141</a> <span> [<a href="https://arxiv.org/pdf/2405.10141">pdf</a>, <a href="https://arxiv.org/format/2405.10141">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202449726">10.1051/0004-6361/202449726 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The flaring activity of blazar AO 0235+164 during year 2021 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Pedrosa%2C+J+E">Juan Escudero Pedrosa</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Moritz%2C+T">Till Moritz</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S">Svetlana Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Tramacere%2C+A">Andrea Tramacere</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">Carolina Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Thum%2C+C">Clemens Thum</a>, <a href="/search/astro-ph?searchtype=author&query=Myserlis%2C+I">Ioannis Myserlis</a>, <a href="/search/astro-ph?searchtype=author&query=Sievers%2C+A">Albrecht Sievers</a>, <a href="/search/astro-ph?searchtype=author&query=Otero-Santos%2C+J">Jorge Otero-Santos</a>, <a href="/search/astro-ph?searchtype=author&query=Morcuende%2C+D">Daniel Morcuende</a>, <a href="/search/astro-ph?searchtype=author&query=L%C3%B3pez-Coto%2C+R">Rub茅n L贸pez-Coto</a>, <a href="/search/astro-ph?searchtype=author&query=D%27Ammando%2C+F">Filippo D'Ammando</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">Giacomo Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Gurwell%2C+M">Mark Gurwell</a>, <a href="/search/astro-ph?searchtype=author&query=G%C3%B3mez%2C+J+L">Jos茅 Luis G贸mez</a>, <a href="/search/astro-ph?searchtype=author&query=Rao%2C+R">Ramprasad Rao</a>, <a href="/search/astro-ph?searchtype=author&query=Keating%2C+G">Garrett Keating</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.10141v1-abstract-short" style="display: inline;"> Context. The blazar AO 0235+164, located at redshift $z=0.94$, has displayed interesting and repeating flaring activity in the past, the latest episodes occurring in 2008 and 2015. In 2020, the source brightened again, starting a new flaring episode that peaked in 2021. Aims. We study the origin and properties of the 2021 flare in relation to previous studies and the historical behavior of the sou… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.10141v1-abstract-full').style.display = 'inline'; document.getElementById('2405.10141v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.10141v1-abstract-full" style="display: none;"> Context. The blazar AO 0235+164, located at redshift $z=0.94$, has displayed interesting and repeating flaring activity in the past, the latest episodes occurring in 2008 and 2015. In 2020, the source brightened again, starting a new flaring episode that peaked in 2021. Aims. We study the origin and properties of the 2021 flare in relation to previous studies and the historical behavior of the source, in particular to the 2008 and 2015 flaring episodes. Methods. We analyze the multi-wavelength photo-polarimetric evolution of the source. From Very Long Baseline Array images, we derive the kinematic parameters of new components associated with the 2021 flare. We use this information to constrain a model for the spectral energy distribution of the emission during the flaring period. We propose an analytical geometric model to test whether the observed wobbling of the jet is consistent with precession. Results. We report the appearance of two new components that are ejected in a different direction than previously, confirming the wobbling of the jet. We find that the direction of ejection is consistent with that of a precessing jet.The derived period independently agrees with the values commonly found in the literature. Modeling of the spectral energy distribution further confirm that the differences between flares can be attributed to geometrical effects. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.10141v1-abstract-full').style.display = 'none'; document.getElementById('2405.10141v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted 15 May 2024</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 689, A56 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.08560">arXiv:2401.08560</a> <span> [<a href="https://arxiv.org/pdf/2401.08560">pdf</a>, <a href="https://arxiv.org/format/2401.08560">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Insights into the broad-band emission of the TeV blazar Mrk 501 during the first X-ray polarization measurements </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Abe%2C+S">S. Abe</a>, <a href="/search/astro-ph?searchtype=author&query=Abhir%2C+J">J. Abhir</a>, <a href="/search/astro-ph?searchtype=author&query=Acciari%2C+V+A">V. A. Acciari</a>, <a href="/search/astro-ph?searchtype=author&query=Aguasca-Cabot%2C+A">A. Aguasca-Cabot</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">I. Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Aniello%2C+T">T. Aniello</a>, <a href="/search/astro-ph?searchtype=author&query=Ansoldi%2C+S">S. Ansoldi</a>, <a href="/search/astro-ph?searchtype=author&query=Antonelli%2C+L+A">L. A. Antonelli</a>, <a href="/search/astro-ph?searchtype=author&query=Engels%2C+A+A">A. Arbet Engels</a>, <a href="/search/astro-ph?searchtype=author&query=Arcaro%2C+C">C. Arcaro</a>, <a href="/search/astro-ph?searchtype=author&query=Asano%2C+K">K. Asano</a>, <a href="/search/astro-ph?searchtype=author&query=Babi%C4%87%2C+A">A. Babi膰</a>, <a href="/search/astro-ph?searchtype=author&query=Baquero%2C+A">A. Baquero</a>, <a href="/search/astro-ph?searchtype=author&query=de+Almeida%2C+U+B">U. Barres de Almeida</a>, <a href="/search/astro-ph?searchtype=author&query=Barrio%2C+J+A">J. A. Barrio</a>, <a href="/search/astro-ph?searchtype=author&query=Batkovi%C4%87%2C+I">I. Batkovi膰</a>, <a href="/search/astro-ph?searchtype=author&query=Bautista%2C+A">A. Bautista</a>, <a href="/search/astro-ph?searchtype=author&query=Baxter%2C+J">J. Baxter</a>, <a href="/search/astro-ph?searchtype=author&query=Gonz%C3%A1lez%2C+J+B">J. Becerra Gonz谩lez</a>, <a href="/search/astro-ph?searchtype=author&query=Bednarek%2C+W">W. Bednarek</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardini%2C+E">E. Bernardini</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardos%2C+M">M. Bernardos</a>, <a href="/search/astro-ph?searchtype=author&query=Bernete%2C+J">J. Bernete</a>, <a href="/search/astro-ph?searchtype=author&query=Berti%2C+A">A. Berti</a>, <a href="/search/astro-ph?searchtype=author&query=Besenrieder%2C+J">J. Besenrieder</a> , et al. (239 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2401.08560v1-abstract-short" style="display: inline;"> We present the first multi-wavelength study of Mrk 501 including very-high-energy (VHE) gamma-ray observations simultaneous to X-ray polarization measurements from the Imaging X-ray Polarimetry Explorer (IXPE). We use radio-to-VHE data from a multi-wavelength campaign organized between 2022-03-01 and 2022-07-19. The observations were performed by MAGIC, Fermi-LAT, NuSTAR, Swift (XRT and UVOT), and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.08560v1-abstract-full').style.display = 'inline'; document.getElementById('2401.08560v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.08560v1-abstract-full" style="display: none;"> We present the first multi-wavelength study of Mrk 501 including very-high-energy (VHE) gamma-ray observations simultaneous to X-ray polarization measurements from the Imaging X-ray Polarimetry Explorer (IXPE). We use radio-to-VHE data from a multi-wavelength campaign organized between 2022-03-01 and 2022-07-19. The observations were performed by MAGIC, Fermi-LAT, NuSTAR, Swift (XRT and UVOT), and several instruments covering the optical and radio bands. During the IXPE pointings, the VHE state is close to the average behavior with a 0.2-1 TeV flux of 20%-50% the emission of the Crab Nebula. Despite the average VHE activity, an extreme X-ray behavior is measured for the first two IXPE pointings in March 2022 with a synchrotron peak frequency >1 keV. For the third IXPE pointing in July 2022, the synchrotron peak shifts towards lower energies and the optical/X-ray polarization degrees drop. The X-ray polarization is systematically higher than at lower energies, suggesting an energy-stratification of the jet. While during the IXPE epochs the polarization angle in the X-ray, optical and radio bands align well, we find a clear discrepancy in the optical and radio polarization angles in the middle of the campaign. We model the broad-band spectra simultaneous to the IXPE pointings assuming a compact zone dominating in the X-rays and VHE, and an extended zone stretching further downstream the jet dominating the emission at lower energies. NuSTAR data allow us to precisely constrain the synchrotron peak and therefore the underlying electron distribution. The change between the different states observed in the three IXPE pointings can be explained by a change of magnetization and/or emission region size, which directly connects the shift of the synchrotron peak to lower energies with the drop in polarization degree. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.08560v1-abstract-full').style.display = 'none'; document.getElementById('2401.08560v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in Astronomy & Astrophysics. 19 pages, 9 figures. Corresponding authors: Lea Heckmann, Axel Arbet Engels, David Paneque</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.04420">arXiv:2401.04420</a> <span> [<a href="https://arxiv.org/pdf/2401.04420">pdf</a>, <a href="https://arxiv.org/format/2401.04420">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ad1ce4">10.3847/1538-4357/ad1ce4 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Detection of X-ray Polarization from the Blazar 1ES 1959+650 with the Imaging X-ray Polarimetry Explorer </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Peirson%2C+A+L">Abel Lawrence Peirson</a>, <a href="/search/astro-ph?searchtype=author&query=Perri%2C+M">Matteo Perri</a>, <a href="/search/astro-ph?searchtype=author&query=Puccetti%2C+S">Simonetta Puccetti</a>, <a href="/search/astro-ph?searchtype=author&query=Rabinowitz%2C+P+L">Pazit L. Rabinowitz</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Savchenko%2C+S+S">Sergey S. Savchenko</a>, <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D">Dmitry Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Bourbah%2C+I+G">Ioakeim G. Bourbah</a>, <a href="/search/astro-ph?searchtype=author&query=Kiehlmann%2C+S">Sebastian Kiehlmann</a>, <a href="/search/astro-ph?searchtype=author&query=Kontopodis%2C+E">Evangelos Kontopodis</a>, <a href="/search/astro-ph?searchtype=author&query=Mandarakas%2C+N">Nikos Mandarakas</a>, <a href="/search/astro-ph?searchtype=author&query=Romanopoulos%2C+S">Stylianos Romanopoulos</a>, <a href="/search/astro-ph?searchtype=author&query=Skalidis%2C+R">Raphael Skalidis</a>, <a href="/search/astro-ph?searchtype=author&query=Vervelaki%2C+A">Anna Vervelaki</a>, <a href="/search/astro-ph?searchtype=author&query=Aceituno%2C+F+J">Francisco Jos茅 Aceituno</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardos%2C+M+I">Maria I. Bernardos</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">Giacomo Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Casanova%2C+V">V铆ctor Casanova</a> , et al. (121 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2401.04420v1-abstract-short" style="display: inline;"> Observations of linear polarization in the 2-8 keV energy range with the Imaging X-ray Polarimetry Explorer (IXPE) explore the magnetic field geometry and dynamics of the regions generating non-thermal radiation in relativistic jets of blazars. These jets, particularly in blazars whose spectral energy distribution peaks at X-ray energies, emit X-rays via synchrotron radiation from high-energy part… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.04420v1-abstract-full').style.display = 'inline'; document.getElementById('2401.04420v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.04420v1-abstract-full" style="display: none;"> Observations of linear polarization in the 2-8 keV energy range with the Imaging X-ray Polarimetry Explorer (IXPE) explore the magnetic field geometry and dynamics of the regions generating non-thermal radiation in relativistic jets of blazars. These jets, particularly in blazars whose spectral energy distribution peaks at X-ray energies, emit X-rays via synchrotron radiation from high-energy particles within the jet. IXPE observations of the X-ray selected BL Lac-type blazar 1ES 1959+650 in 2022 May 3-4 showed a significant linear polarization degree of $螤_\mathrm{x} = 8.0\% \pm 2.3\%$ at an electric-vector position angle $蠄_\mathrm{x} = 123^\circ \pm 8^\circ$. However, in 2022 June 9-12, only an upper limit of $螤_\mathrm{x} \leq 5.1\%$ could be derived (at the 99% confidence level). The degree of optical polarization at that time $螤_\mathrm{O} \sim 5\%$ is comparable to the X-ray measurement. We investigate possible scenarios for these findings, including temporal and geometrical depolarization effects. Unlike some other X-ray selected BL Lac objects, there is no significant chromatic dependence of the measured polarization in 1ES 1959+650, and its low X-ray polarization may be attributed to turbulence in the jet flow with dynamical timescales shorter than 1 day. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.04420v1-abstract-full').style.display = 'none'; document.getElementById('2401.04420v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">16 pages, 4 figures, accepted for publication in The Astrophysical Journal</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> The Astrophysical Journal, 963 (2024) 5 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.15556">arXiv:2312.15556</a> <span> [<a href="https://arxiv.org/pdf/2312.15556">pdf</a>, <a href="https://arxiv.org/format/2312.15556">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Lost in the curve: Investigating the disappearing knots in the blazar 3C 454.3 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Traianou%2C+E">Efthalia Traianou</a>, <a href="/search/astro-ph?searchtype=author&query=Krichbaum%2C+T+P">Thomas P. Krichbaum</a>, <a href="/search/astro-ph?searchtype=author&query=G%C3%B3mez%2C+J+L">Jos茅 L. G贸mez</a>, <a href="/search/astro-ph?searchtype=author&query=Lico%2C+R">Rocco Lico</a>, <a href="/search/astro-ph?searchtype=author&query=Paraschos%2C+G+F">Georgios Filippos Paraschos</a>, <a href="/search/astro-ph?searchtype=author&query=Cho%2C+I">Ilje Cho</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">Eduardo Ros</a>, <a href="/search/astro-ph?searchtype=author&query=Zhao%2C+G">Guang-Yao Zhao</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Dahale%2C+R">Rohan Dahale</a>, <a href="/search/astro-ph?searchtype=author&query=Toscano%2C+T">Teresa Toscano</a>, <a href="/search/astro-ph?searchtype=author&query=Fuentes%2C+A">Antonio Fuentes</a>, <a href="/search/astro-ph?searchtype=author&query=Foschi%2C+M">Marianna Foschi</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">Carolina Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=MacDonald%2C+N">Nicholas MacDonald</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+J">Jae-Young Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">Olivier Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S">Svetlana Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Lobanov%2C+A+P">Andrei P. Lobanov</a>, <a href="/search/astro-ph?searchtype=author&query=Hodgson%2C+J">Jeffrey Hodgson</a>, <a href="/search/astro-ph?searchtype=author&query=Myserlis%2C+I">Ioannis Myserlis</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Ivan Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Zensus%2C+A+J">Anton J. Zensus</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2312.15556v1-abstract-short" style="display: inline;"> One of the most well-known extragalactic sources in the sky, quasar 3C 454.3, shows a curved parsec-scale jet that has been exhaustively monitored with very-long-baseline interferometry (VLBI) over the recent years. In this work, we present a comprehensive analysis of four years of high-frequency VLBI observations at 43 GHz and 86 GHz, between 2013-2017, in total intensity and linear polarization.… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.15556v1-abstract-full').style.display = 'inline'; document.getElementById('2312.15556v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.15556v1-abstract-full" style="display: none;"> One of the most well-known extragalactic sources in the sky, quasar 3C 454.3, shows a curved parsec-scale jet that has been exhaustively monitored with very-long-baseline interferometry (VLBI) over the recent years. In this work, we present a comprehensive analysis of four years of high-frequency VLBI observations at 43 GHz and 86 GHz, between 2013-2017, in total intensity and linear polarization. The images obtained from these observations enabled us to study the jet structure and the magnetic field topology of the source on spatial scales down to 4.6 parsec in projected distance. The kinematic analysis reveals the abrupt vanishing of at least four new superluminal jet features in a characteristic jet region (i.e., region C), which is located at an approximate distance of 0.6 milliarcseconds from the VLBI core. Our results support a model in which the jet bends, directing the relativistic plasma flow almost perfectly toward our line of sight, co-spatially with the region where components appear to stop. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.15556v1-abstract-full').style.display = 'none'; document.getElementById('2312.15556v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 7 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.10732">arXiv:2312.10732</a> <span> [<a href="https://arxiv.org/pdf/2312.10732">pdf</a>, <a href="https://arxiv.org/format/2312.10732">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> First characterization of the emission behavior of Mrk421 from radio to VHE gamma rays with simultaneous X-ray polarization measurements </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Abe%2C+S">S. Abe</a>, <a href="/search/astro-ph?searchtype=author&query=Abhir%2C+J">J. Abhir</a>, <a href="/search/astro-ph?searchtype=author&query=Acciari%2C+V+A">V. A. Acciari</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">I. Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Aniello%2C+T">T. Aniello</a>, <a href="/search/astro-ph?searchtype=author&query=Ansoldi%2C+S">S. Ansoldi</a>, <a href="/search/astro-ph?searchtype=author&query=Antonelli%2C+L+A">L. A. Antonelli</a>, <a href="/search/astro-ph?searchtype=author&query=Engels%2C+A+A">A. Arbet Engels</a>, <a href="/search/astro-ph?searchtype=author&query=Arcaro%2C+C">C. Arcaro</a>, <a href="/search/astro-ph?searchtype=author&query=Artero%2C+M">M. Artero</a>, <a href="/search/astro-ph?searchtype=author&query=Asano%2C+K">K. Asano</a>, <a href="/search/astro-ph?searchtype=author&query=Babi%C4%87%2C+A">A. Babi膰</a>, <a href="/search/astro-ph?searchtype=author&query=Baquero%2C+A">A. Baquero</a>, <a href="/search/astro-ph?searchtype=author&query=de+Almeida%2C+U+B">U. Barres de Almeida</a>, <a href="/search/astro-ph?searchtype=author&query=Barrio%2C+J+A">J. A. Barrio</a>, <a href="/search/astro-ph?searchtype=author&query=Batkovi%C4%87%2C+I">I. Batkovi膰</a>, <a href="/search/astro-ph?searchtype=author&query=Baxter%2C+J">J. Baxter</a>, <a href="/search/astro-ph?searchtype=author&query=Gonz%C3%A1lez%2C+J+B">J. Becerra Gonz谩lez</a>, <a href="/search/astro-ph?searchtype=author&query=Bednarek%2C+W">W. Bednarek</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardini%2C+E">E. Bernardini</a>, <a href="/search/astro-ph?searchtype=author&query=Bernete%2C+J">J. Bernete</a>, <a href="/search/astro-ph?searchtype=author&query=Berti%2C+A">A. Berti</a>, <a href="/search/astro-ph?searchtype=author&query=Besenrieder%2C+J">J. Besenrieder</a>, <a href="/search/astro-ph?searchtype=author&query=Bigongiari%2C+C">C. Bigongiari</a>, <a href="/search/astro-ph?searchtype=author&query=Biland%2C+A">A. Biland</a> , et al. (229 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2312.10732v1-abstract-short" style="display: inline;"> We perform the first broadband study of Mrk421 from radio to TeV gamma rays with simultaneous measurements of the X-ray polarization from IXPE. The data were collected within an extensive multiwavelength campaign organized between May and June 2022 using MAGIC, Fermi-LAT, NuSTAR, XMM-Newton, Swift, and several optical and radio telescopes to complement IXPE. During the IXPE exposures, the measured… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.10732v1-abstract-full').style.display = 'inline'; document.getElementById('2312.10732v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.10732v1-abstract-full" style="display: none;"> We perform the first broadband study of Mrk421 from radio to TeV gamma rays with simultaneous measurements of the X-ray polarization from IXPE. The data were collected within an extensive multiwavelength campaign organized between May and June 2022 using MAGIC, Fermi-LAT, NuSTAR, XMM-Newton, Swift, and several optical and radio telescopes to complement IXPE. During the IXPE exposures, the measured 0.2-1 TeV flux is close to the quiescent state and ranges from 25% to 50% of the Crab Nebula without intra-night variability. Throughout the campaign, the VHE and X-ray emission are positively correlated at a $4蟽$ significance level. The IXPE measurements unveil a X-ray polarization degree that is a factor of 2-5 higher than in the optical/radio bands; that implies an energy-stratified jet in which the VHE photons are emitted co-spatially with the X-rays, in the vicinity of a shock front. The June 2022 observations exhibit a rotation of the X-ray polarization angle. Despite no simultaneous VHE coverage being available during a large fraction of the swing, the Swift-XRT monitoring unveils an X-ray flux increase with a clear spectral hardening. It suggests that flares in high synchrotron peaked blazars can be accompanied by a polarization angle rotation, as observed in some flat spectrum radio quasars. Finally, during the polarization angle rotation, NuSTAR data reveal two contiguous spectral hysteresis loops in opposite directions (clockwise and counter-clockwise), implying important changes in the particle acceleration efficiency on $\sim$hour timescales. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.10732v1-abstract-full').style.display = 'none'; document.getElementById('2312.10732v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in Astronomy & Astrophysics. 29 pages, 22 figures. Corresponding authors: Axel Arbet Engels, Felix Schmuckermaier, David Paneque</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2311.01157">arXiv:2311.01157</a> <span> [<a href="https://arxiv.org/pdf/2311.01157">pdf</a>, <a href="https://arxiv.org/format/2311.01157">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202346885">10.1051/0004-6361/202346885 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Repeating Flaring Activity of Blazar AO 0235+164 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Pedrosa%2C+J+E">Juan Escudero Pedrosa</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Tramacere%2C+A">Andrea Tramacere</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S">Svetlana Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Weaver%2C+Z+R">Z. R. Weaver</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">Carolina Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Thum%2C+C">Clemens Thum</a>, <a href="/search/astro-ph?searchtype=author&query=Myserlis%2C+I">Ioannis Myserlis</a>, <a href="/search/astro-ph?searchtype=author&query=Fuentes%2C+A">Antonio Fuentes</a>, <a href="/search/astro-ph?searchtype=author&query=Traianou%2C+E">Efthalia Traianou</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+J">Jae-Young Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Kramer%2C+J">Joana Kramer</a>, <a href="/search/astro-ph?searchtype=author&query=L%C3%B3pez-Coto%2C+R">Rub茅n L贸pez-Coto</a>, <a href="/search/astro-ph?searchtype=author&query=D%27Ammando%2C+F">Filippo D'Ammando</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardos%2C+M">M. Bernardos</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">Giacomo Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D+A">Dmitriy A. Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Borman%2C+G+A">G. A. Borman</a>, <a href="/search/astro-ph?searchtype=author&query=Grishina%2C+T+S">T. S. Grishina</a>, <a href="/search/astro-ph?searchtype=author&query=Hagen-Thorn%2C+V+A">V. A. Hagen-Thorn</a>, <a href="/search/astro-ph?searchtype=author&query=Kopatskaya%2C+E+N">E. N. Kopatskaya</a>, <a href="/search/astro-ph?searchtype=author&query=Larionova%2C+E+G">E. G. Larionova</a>, <a href="/search/astro-ph?searchtype=author&query=Larionov%2C+V+M">V. M. Larionov</a>, <a href="/search/astro-ph?searchtype=author&query=Larionova%2C+L+V">L. V. Larionova</a> , et al. (5 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2311.01157v1-abstract-short" style="display: inline;"> Context. Blazar AO 0235+164, located at redshift z = 0.94, has undergone several sharp multi-spectral-range flaring episodes during the last decades. In particular, the episodes peaking in 2008 and 2015, that received extensive multi-wavelength coverage, exhibited interesting behavior. Aims. We study the actual origin of these two observed flares by constraining the properties of the observed ph… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.01157v1-abstract-full').style.display = 'inline'; document.getElementById('2311.01157v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.01157v1-abstract-full" style="display: none;"> Context. Blazar AO 0235+164, located at redshift z = 0.94, has undergone several sharp multi-spectral-range flaring episodes during the last decades. In particular, the episodes peaking in 2008 and 2015, that received extensive multi-wavelength coverage, exhibited interesting behavior. Aims. We study the actual origin of these two observed flares by constraining the properties of the observed photo-polarimetric variability, those of the broad-band spectral energy-distribution and the observed time-evolution behavior of the source as seen by ultra-high resolution total-flux and polarimetric Very-long-baseline interferometry (VLBI) imaging. Methods. The analysis of VLBI images allows us to constrain kinematic and geometrical parameters of the 7 mm jet. We use the Discrete Correlation Function to compute the statistical correlation and the delays between emission at different spectral ranges. Multi-epoch modeling of the spectral energy distributions allows us to propose specific models of emission; in particular for the unusual spectral features observed in this source in the X-ray region of the spectrum during strong multi spectral-range flares. Results. We find that these X-ray spectral features can be explained by an emission component originating in a separate particle distribution than the one responsible for the two standard blazar bumps. This is in agreement with the results of our correlation analysis that do not find a strong correlation between the X-rays and the remaining spectral ranges. We find that both external Compton dominated and synchrotron self-Compton dominated models can explain the observed spectral energy distributions. However, synchrotron self-Compton models are strongly favored by the delays and geometrical parameters inferred from the observations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.01157v1-abstract-full').style.display = 'none'; document.getElementById('2311.01157v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.16296">arXiv:2310.16296</a> <span> [<a href="https://arxiv.org/pdf/2310.16296">pdf</a>, <a href="https://arxiv.org/format/2310.16296">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> </div> <p class="title is-5 mathjax"> A Near Magnetic-to-kinetic Energy Equipartition Flare from the Relativistic Jet in AO 0235+164 during 2013-2019 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Cheong%2C+W+Y">Whee Yeon Cheong</a>, <a href="/search/astro-ph?searchtype=author&query=Lee%2C+S">Sang-Sung Lee</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+S">Sang-Hyun Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Kang%2C+S">Sincheol Kang</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+J+Y">Jae Young Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Rani%2C+B">Bindu Rani</a>, <a href="/search/astro-ph?searchtype=author&query=Readhead%2C+A+C+S">Anthony C. S. Readhead</a>, <a href="/search/astro-ph?searchtype=author&query=Kiehlmann%2C+S">Sebastian Kiehlmann</a>, <a href="/search/astro-ph?searchtype=author&query=L%C3%A4hteenm%C3%A4ki%2C+A">Anne L盲hteenm盲ki</a>, <a href="/search/astro-ph?searchtype=author&query=Tornikoski%2C+M">Merja Tornikoski</a>, <a href="/search/astro-ph?searchtype=author&query=Tammi%2C+J">Joni Tammi</a>, <a href="/search/astro-ph?searchtype=author&query=Ramakrishnan%2C+V">Venkatessh Ramakrishnan</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Fuentes%2C+A">Antonio Fuentes</a>, <a href="/search/astro-ph?searchtype=author&query=Traianou%2C+E">Efthalia Traianou</a>, <a href="/search/astro-ph?searchtype=author&query=Escudero%2C+J">Juan Escudero</a>, <a href="/search/astro-ph?searchtype=author&query=Thum%2C+C">Clemens Thum</a>, <a href="/search/astro-ph?searchtype=author&query=Myserlis%2C+I">Ioannis Myserlis</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">Carolina Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Gurwell%2C+M">Mark Gurwell</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2310.16296v1-abstract-short" style="display: inline;"> We present the multiwavelength flaring activity of the blazar AO 0235+164 during its recent active period from 2013 to 2019. From a discrete correlation function (DCF) analysis, we find a significant (>95%) correlation between radio and $纬$-ray light curves with flares at longer wavelengths following flares at shorter wavelengths. We identify a new jet component in 43 GHz VLBA data that was ejecte… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.16296v1-abstract-full').style.display = 'inline'; document.getElementById('2310.16296v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.16296v1-abstract-full" style="display: none;"> We present the multiwavelength flaring activity of the blazar AO 0235+164 during its recent active period from 2013 to 2019. From a discrete correlation function (DCF) analysis, we find a significant (>95%) correlation between radio and $纬$-ray light curves with flares at longer wavelengths following flares at shorter wavelengths. We identify a new jet component in 43 GHz VLBA data that was ejected from the radio core on MJD $57246^{+26}_{-30}$ (2015 August 12), during the peak of the 2015 radio flare. From the analysis of the jet component, we derived a Doppler factor of $未_{\rm var}=28.5\pm8.4$, a bulk Lorentz factor of $螕=16.8^{+3.6}_{-3.1}$, and an intrinsic viewing angle of $胃_{\rm v}=1.42^{+1.07}_{-0.52}\textrm{ degrees}$. Investigation of the quasi-simultaneous radio data revealed a partially absorbed spectrum with the turnover frequency varying in the range of $10-70$ GHz and the peak flux density varying in the range of $0.7-4$ Jy. We find the synchrotron self-absorption magnetic field strength to be $B_{\rm SSA}=15.3^{+12.6}_{-14.0}$ mG at the peak of the 2015 radio flare, which is comparable to the equipartition magnetic field strength of $B_{\rm EQ}=43.6^{+10.6}_{-10.4}$ mG calculated for the same epoch. Additional analysis of the radio emission region in the relativistic jet of AO 0235+164 suggests that it did not significantly deviate from equipartition during its recent flaring activity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.16296v1-abstract-full').style.display = 'none'; document.getElementById('2310.16296v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 11 figures, 4 tables; Accepted for publication in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.11510">arXiv:2310.11510</a> <span> [<a href="https://arxiv.org/pdf/2310.11510">pdf</a>, <a href="https://arxiv.org/format/2310.11510">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Observations of Low and Intermediate Spectral Peak Blazars with the Imaging X-ray Polarimetry Explorer </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Lalla%2C+N">Niccolo Di Lalla</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Omodei%2C+N">Nicola Omodei</a>, <a href="/search/astro-ph?searchtype=author&query=Peirson%2C+A+L">Abel L. Peirson</a>, <a href="/search/astro-ph?searchtype=author&query=Perri%2C+M">Matteo Perri</a>, <a href="/search/astro-ph?searchtype=author&query=Puccetti%2C+S">Simonetta Puccetti</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Ivan Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">Giacomo Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Berdyugin%2C+A+V">Andrei V. Berdyugin</a>, <a href="/search/astro-ph?searchtype=author&query=Cavazzuti%2C+E">Elisabetta Cavazzuti</a>, <a href="/search/astro-ph?searchtype=author&query=Cavero%2C+N+R">Nicole Rodriguez Cavero</a>, <a href="/search/astro-ph?searchtype=author&query=Donnarumma%2C+I">Immacolata Donnarumma</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Jormanainen%2C+J">Jenni Jormanainen</a>, <a href="/search/astro-ph?searchtype=author&query=Krawczynski%2C+H">Henric Krawczynski</a>, <a href="/search/astro-ph?searchtype=author&query=Lindfors%2C+E">Elina Lindfors</a>, <a href="/search/astro-ph?searchtype=author&query=Marin%2C+F">Frederic Marin</a>, <a href="/search/astro-ph?searchtype=author&query=Massaro%2C+F">Francesco Massaro</a>, <a href="/search/astro-ph?searchtype=author&query=Pacciani%2C+L">Luigi Pacciani</a> , et al. (133 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2310.11510v2-abstract-short" style="display: inline;"> We present X-ray polarimetry observations from the Imaging X-ray Polarimetry Explorer (IXPE) of three low spectral peak and one intermediate spectral peak blazars, namely 3C 273, 3C 279, 3C 454.3, and S5 0716+714. For none of these objects was IXPE able to detect X-ray polarization at the 3$蟽$ level. However, we placed upper limits on the polarization degree at $\sim$10-30\%. The undetected polari… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.11510v2-abstract-full').style.display = 'inline'; document.getElementById('2310.11510v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.11510v2-abstract-full" style="display: none;"> We present X-ray polarimetry observations from the Imaging X-ray Polarimetry Explorer (IXPE) of three low spectral peak and one intermediate spectral peak blazars, namely 3C 273, 3C 279, 3C 454.3, and S5 0716+714. For none of these objects was IXPE able to detect X-ray polarization at the 3$蟽$ level. However, we placed upper limits on the polarization degree at $\sim$10-30\%. The undetected polarizations favor models where the X-ray band is dominated by unpolarized photons upscattered by relativistic electrons in the jets of blazars, although hadronic models are not completely eliminated. We discuss the X-ray polarization upper limits in the context of our contemporaneous multiwavelength polarization campaigns. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.11510v2-abstract-full').style.display = 'none'; document.getElementById('2310.11510v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 10 figures, 6 tables; submitted to the Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.00039">arXiv:2308.00039</a> <span> [<a href="https://arxiv.org/pdf/2308.00039">pdf</a>, <a href="https://arxiv.org/format/2308.00039">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> IXPE and multi-wavelength observations of blazar PG 1553+113 reveal an orphan optical polarization swing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Perri%2C+M">Matteo Perri</a>, <a href="/search/astro-ph?searchtype=author&query=Puccetti%2C+S">Simonetta Puccetti</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Cavero%2C+N+R">Nicole Rodriguez Cavero</a>, <a href="/search/astro-ph?searchtype=author&query=Tavecchio%2C+F">Fabrizio Tavecchio</a>, <a href="/search/astro-ph?searchtype=author&query=Donnarumma%2C+I">Immacolata Donnarumma</a>, <a href="/search/astro-ph?searchtype=author&query=Laurenti%2C+M">Marco Laurenti</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Pacciani%2C+L">Luigi Pacciani</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Aceituno%2C+F+J">Francisco Jos茅 Aceituno</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">Giacomo Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Casanova%2C+V">V铆ctor Casanova</a>, <a href="/search/astro-ph?searchtype=author&query=Ag%C3%ADs-Gonz%C3%A1lez%2C+B">Beatriz Ag铆s-Gonz谩lez</a>, <a href="/search/astro-ph?searchtype=author&query=Sota%2C+A">Alfredo Sota</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">Carolina Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Escudero%2C+J">Juan Escudero</a>, <a href="/search/astro-ph?searchtype=author&query=Myserlis%2C+I">Ioannis Myserlis</a>, <a href="/search/astro-ph?searchtype=author&query=Sievers%2C+A">Albrecht Sievers</a>, <a href="/search/astro-ph?searchtype=author&query=Kouch%2C+P+M">Pouya M. Kouch</a> , et al. (97 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2308.00039v1-abstract-short" style="display: inline;"> The lower energy peak of the spectral energy distribution of blazars has commonly been ascribed to synchrotron radiation from relativistic particles in the jets. Despite the consensus regarding jet emission processes, the particle acceleration mechanism is still debated. Here, we present the first X-ray polarization observations of PG 1553+113, a high-synchrotron-peak blazar observed by the Imagin… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.00039v1-abstract-full').style.display = 'inline'; document.getElementById('2308.00039v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.00039v1-abstract-full" style="display: none;"> The lower energy peak of the spectral energy distribution of blazars has commonly been ascribed to synchrotron radiation from relativistic particles in the jets. Despite the consensus regarding jet emission processes, the particle acceleration mechanism is still debated. Here, we present the first X-ray polarization observations of PG 1553+113, a high-synchrotron-peak blazar observed by the Imaging X-ray Polarimetry Explorer (IXPE). We detect an X-ray polarization degree of $(10\pm2)\%$ along an electric-vector position angle of $蠄_X=86^{\circ}\pm8^{\circ}$. At the same time, the radio and optical polarization degrees are lower by a factor of $\sim$3. During our IXPE pointing, we observed the first orphan optical polarization swing of the IXPE era, as the optical angle of PG 1553+113 underwent a smooth monotonic rotation by about 125$^\circ$, with a rate of $\sim$17 degrees per day. We do not find evidence of a similar rotation in either radio or X-rays, which suggests that the X-ray and optically emitting regions are separate or, at most, partially co-spatial. Our spectro-polarimetric results provide further evidence that the steady-state X-ray emission in blazars originates in a shock-accelerated and energy-stratified electron population. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.00039v1-abstract-full').style.display = 'none'; document.getElementById('2308.00039v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 31 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for pubblication in The Astrophysical Journal Letters. 3 Figures, 13 pages</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.06151">arXiv:2307.06151</a> <span> [<a href="https://arxiv.org/pdf/2307.06151">pdf</a>, <a href="https://arxiv.org/format/2307.06151">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202346778">10.1051/0004-6361/202346778 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The RoboPol sample of optical polarimetric standards </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D">D. Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Maharana%2C+S">S. Maharana</a>, <a href="/search/astro-ph?searchtype=author&query=Bouzelou%2C+F">F. Bouzelou</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">C. Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Gjerl%C3%B8w%2C+E">E. Gjerl酶w</a>, <a href="/search/astro-ph?searchtype=author&query=Jormanainen%2C+J">J. Jormanainen</a>, <a href="/search/astro-ph?searchtype=author&query=Kiehlmann%2C+S">S. Kiehlmann</a>, <a href="/search/astro-ph?searchtype=author&query=Kypriotakis%2C+J+A">J. A. Kypriotakis</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">I. Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Mandarakas%2C+N">N. Mandarakas</a>, <a href="/search/astro-ph?searchtype=author&query=Markopoulioti%2C+L">L. Markopoulioti</a>, <a href="/search/astro-ph?searchtype=author&query=Panopoulou%2C+G+V">G. V. Panopoulou</a>, <a href="/search/astro-ph?searchtype=author&query=Pelgrims%2C+V">V. Pelgrims</a>, <a href="/search/astro-ph?searchtype=author&query=Pouliasi%2C+A">A. Pouliasi</a>, <a href="/search/astro-ph?searchtype=author&query=Romanopoulos%2C+S">S. Romanopoulos</a>, <a href="/search/astro-ph?searchtype=author&query=Skalidis%2C+R">R. Skalidis</a>, <a href="/search/astro-ph?searchtype=author&query=Anche%2C+R+M">R. M. Anche</a>, <a href="/search/astro-ph?searchtype=author&query=Angelakis%2C+E">E. Angelakis</a>, <a href="/search/astro-ph?searchtype=author&query=Antoniadis%2C+J">J. Antoniadis</a>, <a href="/search/astro-ph?searchtype=author&query=Medhi%2C+B+J">B. J. Medhi</a>, <a href="/search/astro-ph?searchtype=author&query=Hovatta%2C+T">T. Hovatta</a>, <a href="/search/astro-ph?searchtype=author&query=Kus%2C+A">A. Kus</a>, <a href="/search/astro-ph?searchtype=author&query=Kylafis%2C+N">N. Kylafis</a>, <a href="/search/astro-ph?searchtype=author&query=Mahabal%2C+A">A. Mahabal</a>, <a href="/search/astro-ph?searchtype=author&query=Myserlis%2C+I">I. Myserlis</a> , et al. (12 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2307.06151v1-abstract-short" style="display: inline;"> Optical polarimeters are typically calibrated using measurements of stars with known and stable polarization parameters. However, there is a lack of such stars available across the sky. Many of the currently available standards are not suitable for medium and large telescopes due to their high brightness. Moreover, as we find, some of the used polarimetric standards are in fact variable or have po… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.06151v1-abstract-full').style.display = 'inline'; document.getElementById('2307.06151v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.06151v1-abstract-full" style="display: none;"> Optical polarimeters are typically calibrated using measurements of stars with known and stable polarization parameters. However, there is a lack of such stars available across the sky. Many of the currently available standards are not suitable for medium and large telescopes due to their high brightness. Moreover, as we find, some of the used polarimetric standards are in fact variable or have polarization parameters that differ from their cataloged values. Our goal is to establish a sample of stable standards suitable for calibrating linear optical polarimeters with an accuracy down to $10^{-3}$ in fractional polarization. For five years, we have been running a monitoring campaign of a sample of standard candidates comprised of 107 stars distributed across the northern sky. We analyzed the variability of the linear polarization of these stars, taking into account the non-Gaussian nature of fractional polarization measurements. For a subsample of nine stars, we also performed multiband polarization measurements. We created a new catalog of 65 stars (see Table 2) that are stable, have small uncertainties of measured polarimetric parameters, and can be used as calibrators of polarimeters at medium- and large-size telescopes. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.06151v1-abstract-full').style.display = 'none'; document.getElementById('2307.06151v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 677, A144 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.13898">arXiv:2305.13898</a> <span> [<a href="https://arxiv.org/pdf/2305.13898">pdf</a>, <a href="https://arxiv.org/format/2305.13898">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/2041-8213/acd242">10.3847/2041-8213/acd242 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> X-ray Polarization of BL Lacertae in Outburst </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Peirson%2C+A+L">Abel L. Peirson</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Pacciani%2C+L">Luigi Pacciani</a>, <a href="/search/astro-ph?searchtype=author&query=Romani%2C+R+W">Roger W. Romani</a>, <a href="/search/astro-ph?searchtype=author&query=Wu%2C+K">Kinwah Wu</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Lalla%2C+N">Niccolo Di Lalla</a>, <a href="/search/astro-ph?searchtype=author&query=Omodei%2C+N">Nicola Omodei</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Ivan Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Kouch%2C+P+M">Pouya M. Kouch</a>, <a href="/search/astro-ph?searchtype=author&query=Lindfors%2C+E">Elina Lindfors</a>, <a href="/search/astro-ph?searchtype=author&query=Aceituno%2C+F+J">Francisco Jose Aceituno</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardos%2C+M+I">Maria I. Bernardos</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">Giacomo Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Casanova%2C+V">Victor Casanova</a>, <a href="/search/astro-ph?searchtype=author&query=Garcia-Comas%2C+M">Maya Garcia-Comas</a>, <a href="/search/astro-ph?searchtype=author&query=Agis-Gonzalez%2C+B">Beatriz Agis-Gonzalez</a>, <a href="/search/astro-ph?searchtype=author&query=Husillos%2C+C">Cesar Husillos</a>, <a href="/search/astro-ph?searchtype=author&query=Marchini%2C+A">Alessandro Marchini</a> , et al. (106 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.13898v2-abstract-short" style="display: inline;"> We report the first $> 99\%$ confidence detection of X-ray polarization in BL Lacertae. During a recent X-ray/$纬$-ray outburst, a 287 ksec observation (2022 November 27-30) was taken using the Imaging X-ray Polarimetry Explorer ({\it IXPE}), together with contemporaneous multiwavelength observations from the Neil Gehrels {\it Swift} observatory and {\it XMM-Newton} in soft X-rays (0.3--10~keV), {\… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.13898v2-abstract-full').style.display = 'inline'; document.getElementById('2305.13898v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.13898v2-abstract-full" style="display: none;"> We report the first $> 99\%$ confidence detection of X-ray polarization in BL Lacertae. During a recent X-ray/$纬$-ray outburst, a 287 ksec observation (2022 November 27-30) was taken using the Imaging X-ray Polarimetry Explorer ({\it IXPE}), together with contemporaneous multiwavelength observations from the Neil Gehrels {\it Swift} observatory and {\it XMM-Newton} in soft X-rays (0.3--10~keV), {\it NuSTAR} in hard X-rays (3--70~keV), and optical polarization from the Calar Alto, and Perkins Telescope observatories. Our contemporaneous X-ray data suggest that the {\it IXPE} energy band is at the crossover between the low- and high-frequency blazar emission humps. The source displays significant variability during the observation, and we measure polarization in three separate time bins. Contemporaneous X-ray spectra allow us to determine the relative contribution from each emission hump. We find $>99\%$ confidence X-ray polarization $螤_{2-4{\rm keV}} = 21.7^{+5.6}_{-7.9}\%$ and electric vector polarization angle $蠄_{2-4{\rm keV}} = -28.7 \pm 8.7^{\circ}$ in the time bin with highest estimated synchrotron flux contribution. We discuss possible implications of our observations, including previous {\it IXPE} BL Lacertae pointings, tentatively concluding that synchrotron self-Compton emission dominates over hadronic emission processes during the observed epochs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.13898v2-abstract-full').style.display = 'none'; document.getElementById('2305.13898v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted to ApJL. 16 pages, 8 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.13497">arXiv:2305.13497</a> <span> [<a href="https://arxiv.org/pdf/2305.13497">pdf</a>, <a href="https://arxiv.org/format/2305.13497">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Discovery of X-ray polarization angle rotation in active galaxy Mrk 421 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Ehlert%2C+S+R">Steven R. Ehlert</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Donnarumma%2C+I">Immacolata Donnarumma</a>, <a href="/search/astro-ph?searchtype=author&query=Tavecchio%2C+F">Fabrizio Tavecchio</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Kiehlmann%2C+S">Sebastian Kiehlmann</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Puccetti%2C+S">Simonetta Puccetti</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Perri%2C+M">Matteo Perri</a>, <a href="/search/astro-ph?searchtype=author&query=Pacciani%2C+L">Luigi Pacciani</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Romani%2C+R+W">Roger W. Romani</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D">Dmitry Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Bourbah%2C+I+G">Ioakeim G. Bourbah</a>, <a href="/search/astro-ph?searchtype=author&query=Kontopodis%2C+E">Evangelos Kontopodis</a>, <a href="/search/astro-ph?searchtype=author&query=Mandarakas%2C+N">Nikos Mandarakas</a>, <a href="/search/astro-ph?searchtype=author&query=Romanopoulos%2C+S">Stylianos Romanopoulos</a>, <a href="/search/astro-ph?searchtype=author&query=Skalidis%2C+R">Raphael Skalidis</a> , et al. (118 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.13497v1-abstract-short" style="display: inline;"> The magnetic field conditions in astrophysical relativistic jets can be probed by multiwavelength polarimetry, which has been recently extended to X-rays. For example, one can track how the magnetic field changes in the flow of the radiating particles by observing rotations of the electric vector position angle $唯$. Here we report the discovery of a $唯_{\mathrm x}$ rotation in the X-ray band in th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.13497v1-abstract-full').style.display = 'inline'; document.getElementById('2305.13497v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.13497v1-abstract-full" style="display: none;"> The magnetic field conditions in astrophysical relativistic jets can be probed by multiwavelength polarimetry, which has been recently extended to X-rays. For example, one can track how the magnetic field changes in the flow of the radiating particles by observing rotations of the electric vector position angle $唯$. Here we report the discovery of a $唯_{\mathrm x}$ rotation in the X-ray band in the blazar Mrk 421 at an average flux state. Across the 5 days of Imaging X-ray Polarimetry Explorer (IXPE) observations of 4-6 and 7-9 June 2022, $唯_{\mathrm x}$ rotated in total by $\geq360^\circ$. Over the two respective date ranges, we find constant, within uncertainties, rotation rates ($80 \pm 9$ and $91 \pm 8 ^\circ/\rm day$) and polarization degrees ($螤_{\mathrm x}=10\%\pm1\%$). Simulations of a random walk of the polarization vector indicate that it is unlikely that such rotation(s) are produced by a stochastic process. The X-ray emitting site does not completely overlap the radio/infrared/optical emission sites, as no similar rotation of $唯$ was observed in quasi-simultaneous data at longer wavelengths. We propose that the observed rotation was caused by a helical magnetic structure in the jet, illuminated in the X-rays by a localized shock propagating along this helix. The optically emitting region likely lies in a sheath surrounding an inner spine where the X-ray radiation is released. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.13497v1-abstract-full').style.display = 'none'; document.getElementById('2305.13497v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.13252">arXiv:2304.13252</a> <span> [<a href="https://arxiv.org/pdf/2304.13252">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="General Relativity and Quantum Cosmology">gr-qc</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41586-023-05843-w">10.1038/s41586-023-05843-w <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A ring-like accretion structure in M87 connecting its black hole and jet </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Lu%2C+R">Ru-Sen Lu</a>, <a href="/search/astro-ph?searchtype=author&query=Asada%2C+K">Keiichi Asada</a>, <a href="/search/astro-ph?searchtype=author&query=Krichbaum%2C+T+P">Thomas P. Krichbaum</a>, <a href="/search/astro-ph?searchtype=author&query=Park%2C+J">Jongho Park</a>, <a href="/search/astro-ph?searchtype=author&query=Tazaki%2C+F">Fumie Tazaki</a>, <a href="/search/astro-ph?searchtype=author&query=Pu%2C+H">Hung-Yi Pu</a>, <a href="/search/astro-ph?searchtype=author&query=Nakamura%2C+M">Masanori Nakamura</a>, <a href="/search/astro-ph?searchtype=author&query=Lobanov%2C+A">Andrei Lobanov</a>, <a href="/search/astro-ph?searchtype=author&query=Hada%2C+K">Kazuhiro Hada</a>, <a href="/search/astro-ph?searchtype=author&query=Akiyama%2C+K">Kazunori Akiyama</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+J">Jae-Young Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Marti-Vidal%2C+I">Ivan Marti-Vidal</a>, <a href="/search/astro-ph?searchtype=author&query=G%C3%B3mez%2C+J+L">Jos茅 L. G贸mez</a>, <a href="/search/astro-ph?searchtype=author&query=Kawashima%2C+T">Tomohisa Kawashima</a>, <a href="/search/astro-ph?searchtype=author&query=Yuan%2C+F">Feng Yuan</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">Eduardo Ros</a>, <a href="/search/astro-ph?searchtype=author&query=Alef%2C+W">Walter Alef</a>, <a href="/search/astro-ph?searchtype=author&query=Britzen%2C+S">Silke Britzen</a>, <a href="/search/astro-ph?searchtype=author&query=Bremer%2C+M">Michael Bremer</a>, <a href="/search/astro-ph?searchtype=author&query=Broderick%2C+A+E">Avery E. Broderick</a>, <a href="/search/astro-ph?searchtype=author&query=Doi%2C+A">Akihiro Doi</a>, <a href="/search/astro-ph?searchtype=author&query=Giovannini%2C+G">Gabriele Giovannini</a>, <a href="/search/astro-ph?searchtype=author&query=Giroletti%2C+M">Marcello Giroletti</a>, <a href="/search/astro-ph?searchtype=author&query=Ho%2C+P+T+P">Paul T. P. Ho</a>, <a href="/search/astro-ph?searchtype=author&query=Honma%2C+M">Mareki Honma</a> , et al. (96 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2304.13252v1-abstract-short" style="display: inline;"> The nearby radio galaxy M87 is a prime target for studying black hole accretion and jet formation^{1,2}. Event Horizon Telescope observations of M87 in 2017, at a wavelength of 1.3 mm, revealed a ring-like structure, which was interpreted as gravitationally lensed emission around a central black hole^3. Here we report images of M87 obtained in 2018, at a wavelength of 3.5 mm, showing that the comp… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.13252v1-abstract-full').style.display = 'inline'; document.getElementById('2304.13252v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.13252v1-abstract-full" style="display: none;"> The nearby radio galaxy M87 is a prime target for studying black hole accretion and jet formation^{1,2}. Event Horizon Telescope observations of M87 in 2017, at a wavelength of 1.3 mm, revealed a ring-like structure, which was interpreted as gravitationally lensed emission around a central black hole^3. Here we report images of M87 obtained in 2018, at a wavelength of 3.5 mm, showing that the compact radio core is spatially resolved. High-resolution imaging shows a ring-like structure of 8.4_{-1.1}^{+0.5} Schwarzschild radii in diameter, approximately 50% larger than that seen at 1.3 mm. The outer edge at 3.5 mm is also larger than that at 1.3 mm. This larger and thicker ring indicates a substantial contribution from the accretion flow with absorption effects in addition to the gravitationally lensed ring-like emission. The images show that the edge-brightened jet connects to the accretion flow of the black hole. Close to the black hole, the emission profile of the jet-launching region is wider than the expected profile of a black-hole-driven jet, suggesting the possible presence of a wind associated with the accretion flow. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.13252v1-abstract-full').style.display = 'none'; document.getElementById('2304.13252v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">50 pages, 18 figures, 3 tables, author's version of the paper published in Nature</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2211.13764">arXiv:2211.13764</a> <span> [<a href="https://arxiv.org/pdf/2211.13764">pdf</a>, <a href="https://arxiv.org/format/2211.13764">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/2041-8213/aca281">10.3847/2041-8213/aca281 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> X-ray Polarization Observations of BL Lacertae </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Perri%2C+M">Matteo Perri</a>, <a href="/search/astro-ph?searchtype=author&query=Puccetti%2C+S">Simonetta Puccetti</a>, <a href="/search/astro-ph?searchtype=author&query=Cavazzuti%2C+E">Elisabetta Cavazzuti</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Ehlert%2C+S+R">Steven R. Ehlert</a>, <a href="/search/astro-ph?searchtype=author&query=Madejski%2C+G">Grzegorz Madejski</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Ag%C3%ADs-Gonz%C3%A1lez%2C+B">Beatriz Ag铆s-Gonz谩lez</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">Giacomo Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardos%2C+M+I">Maria I. Bernardos</a>, <a href="/search/astro-ph?searchtype=author&query=Casanova%2C+V">V铆ctor Casanova</a>, <a href="/search/astro-ph?searchtype=author&query=Garc%C3%ADa-Comas%2C+M">Maya Garc铆a-Comas</a>, <a href="/search/astro-ph?searchtype=author&query=Husillos%2C+C">C茅sar Husillos</a>, <a href="/search/astro-ph?searchtype=author&query=Marchini%2C+A">Alessandro Marchini</a>, <a href="/search/astro-ph?searchtype=author&query=Sota%2C+A">Alfredo Sota</a>, <a href="/search/astro-ph?searchtype=author&query=Kouch%2C+P+M">Pouya M. Kouch</a>, <a href="/search/astro-ph?searchtype=author&query=Borman%2C+G+A">George A. Borman</a>, <a href="/search/astro-ph?searchtype=author&query=Kopatskaya%2C+E+N">Evgenia N. Kopatskaya</a> , et al. (121 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2211.13764v1-abstract-short" style="display: inline;"> Blazars are a class of jet-dominated active galactic nuclei with a typical double-humped spectral energy distribution. It is of common consensus the Synchrotron emission to be responsible for the low frequency peak, while the origin of the high frequency hump is still debated. The analysis of X-rays and their polarization can provide a valuable tool to understand the physical mechanisms responsibl… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.13764v1-abstract-full').style.display = 'inline'; document.getElementById('2211.13764v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2211.13764v1-abstract-full" style="display: none;"> Blazars are a class of jet-dominated active galactic nuclei with a typical double-humped spectral energy distribution. It is of common consensus the Synchrotron emission to be responsible for the low frequency peak, while the origin of the high frequency hump is still debated. The analysis of X-rays and their polarization can provide a valuable tool to understand the physical mechanisms responsible for the origin of high-energy emission of blazars. We report the first observations of BL Lacertae performed with the Imaging X-ray Polarimetry Explorer ({IXPE}), from which an upper limit to the polarization degree $螤_X<$12.6\% was found in the 2-8 keV band. We contemporaneously measured the polarization in radio, infrared, and optical wavelengths. Our multiwavelength polarization analysis disfavors a significant contribution of proton synchrotron radiation to the X-ray emission at these epochs. Instead, it supports a leptonic origin for the X-ray emission in BL Lac. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.13764v1-abstract-full').style.display = 'none'; document.getElementById('2211.13764v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">17 pages, 5 figures, accepted for publication in ApJL</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> 2023, ApJ Letters, 942, L10 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.02547">arXiv:2210.02547</a> <span> [<a href="https://arxiv.org/pdf/2210.02547">pdf</a>, <a href="https://arxiv.org/format/2210.02547">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/acc181">10.3847/1538-4365/acc181 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Multi-messenger characterization of Mrk 501 during historically low X-ray and $纬$-ray activity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=MAGIC+collaboration"> MAGIC collaboration</a>, <a href="/search/astro-ph?searchtype=author&query=Abe%2C+H">H. Abe</a>, <a href="/search/astro-ph?searchtype=author&query=Abe%2C+S">S. Abe</a>, <a href="/search/astro-ph?searchtype=author&query=Acciari%2C+V+A">V. A. Acciari</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">I. Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Aniello%2C+T">T. Aniello</a>, <a href="/search/astro-ph?searchtype=author&query=Ansoldi%2C+S">S. Ansoldi</a>, <a href="/search/astro-ph?searchtype=author&query=Antonelli%2C+L+A">L. A. Antonelli</a>, <a href="/search/astro-ph?searchtype=author&query=Engels%2C+A+A">A. Arbet Engels</a>, <a href="/search/astro-ph?searchtype=author&query=Arcaro%2C+C">C. Arcaro</a>, <a href="/search/astro-ph?searchtype=author&query=Artero%2C+M">M. Artero</a>, <a href="/search/astro-ph?searchtype=author&query=Asano%2C+K">K. Asano</a>, <a href="/search/astro-ph?searchtype=author&query=Baack%2C+D">D. Baack</a>, <a href="/search/astro-ph?searchtype=author&query=Babi%C4%87%2C+A">A. Babi膰</a>, <a href="/search/astro-ph?searchtype=author&query=Baquero%2C+A">A. Baquero</a>, <a href="/search/astro-ph?searchtype=author&query=de+Almeida%2C+U+B">U. Barres de Almeida</a>, <a href="/search/astro-ph?searchtype=author&query=Barrio%2C+J+A">J. A. Barrio</a>, <a href="/search/astro-ph?searchtype=author&query=Batkovi%C4%87%2C+I">I. Batkovi膰</a>, <a href="/search/astro-ph?searchtype=author&query=Baxter%2C+J">J. Baxter</a>, <a href="/search/astro-ph?searchtype=author&query=Gonz%C3%A1lez%2C+J+B">J. Becerra Gonz谩lez</a>, <a href="/search/astro-ph?searchtype=author&query=Bednarek%2C+W">W. Bednarek</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardini%2C+E">E. Bernardini</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardos%2C+M">M. Bernardos</a>, <a href="/search/astro-ph?searchtype=author&query=Berti%2C+A">A. Berti</a>, <a href="/search/astro-ph?searchtype=author&query=Besenrieder%2C+J">J. Besenrieder</a> , et al. (300 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2210.02547v3-abstract-short" style="display: inline;"> We study the broadband emission of Mrk 501 using multi-wavelength observations from 2017 to 2020 performed with a multitude of instruments, involving, among others, MAGIC, Fermi-LAT, NuSTAR, Swift, GASP-WEBT, and OVRO. Mrk 501 showed an extremely low broadband activity, which may help to unravel its baseline emission. Nonetheless, significant flux variations are detected at all wavebands, with the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.02547v3-abstract-full').style.display = 'inline'; document.getElementById('2210.02547v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.02547v3-abstract-full" style="display: none;"> We study the broadband emission of Mrk 501 using multi-wavelength observations from 2017 to 2020 performed with a multitude of instruments, involving, among others, MAGIC, Fermi-LAT, NuSTAR, Swift, GASP-WEBT, and OVRO. Mrk 501 showed an extremely low broadband activity, which may help to unravel its baseline emission. Nonetheless, significant flux variations are detected at all wavebands, with the highest occurring at X-rays and very-high-energy (VHE) $纬$-rays. A significant correlation ($>$3$蟽$) between X-rays and VHE $纬$-rays is measured, supporting leptonic scenarios to explain the variable parts of the emission, also during low activity. This is further supported when we extend our data from 2008 to 2020, and identify, for the first time, significant correlations between Swift-XRT and Fermi-LAT. We additionally find correlations between high-energy $纬$-rays and radio, with the radio lagging by more than 100 days, placing the $纬$-ray emission zone upstream of the radio-bright regions in the jet. Furthermore, Mrk 501 showed a historically low activity in X-rays and VHE $纬$-rays from mid-2017 to mid-2019 with a stable VHE flux ($>$0.2 TeV) of 5% the emission of the Crab Nebula. The broadband spectral energy distribution (SED) of this 2-year-long low-state, the potential baseline emission of Mrk 501, can be characterized with one-zone leptonic models, and with (lepto)-hadronic models fulfilling neutrino flux constraints from IceCube. We explore the time evolution of the SED towards the low-state, revealing that the stable baseline emission may be ascribed to a standing shock, and the variable emission to an additional expanding or traveling shock. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.02547v3-abstract-full').style.display = 'none'; document.getElementById('2210.02547v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">55 pages, 30 figures, 14 tables, accepted by APJS. Corresponding authors are L. Heckmann, D. Paneque, S. Gasparyan, M. Cerruti, and N. Sahakyan</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJS 266 37 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2209.13393">arXiv:2209.13393</a> <span> [<a href="https://arxiv.org/pdf/2209.13393">pdf</a>, <a href="https://arxiv.org/format/2209.13393">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202244978">10.1051/0004-6361/202244978 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Discriminating power of milli-lensing observations for dark matter models </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Loudas%2C+N">Nick Loudas</a>, <a href="/search/astro-ph?searchtype=author&query=Pavlidou%2C+V">Vasiliki Pavlidou</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">Carolina Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Tassis%2C+K">Kostas Tassis</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2209.13393v1-abstract-short" style="display: inline;"> The nature of dark matter (DM) is still under intense debate. Sub-galactic scales are particularly critical, as different, currently viable DM models make diverse predictions on the expected abundance and density profile of DM haloes on these scales. We investigate the ability of sub-galactic DM haloes to act as strong lenses on background compact sources, producing gravitational lensing events on… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.13393v1-abstract-full').style.display = 'inline'; document.getElementById('2209.13393v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2209.13393v1-abstract-full" style="display: none;"> The nature of dark matter (DM) is still under intense debate. Sub-galactic scales are particularly critical, as different, currently viable DM models make diverse predictions on the expected abundance and density profile of DM haloes on these scales. We investigate the ability of sub-galactic DM haloes to act as strong lenses on background compact sources, producing gravitational lensing events on milli-arcsecond scales (milli-lenses), for different DM models. For each DM scenario, we explore whether a sample of $\sim$ 5000 distant sources is sufficient to detect at least one milli-lens. We develop a semi-analytical model to estimate the milli-lensing optical depth as a function of the source's redshift for various DM models. We employ the Press-Schechter formalism, as well as results from recent N-body simulations to compute the halo mass function, taking into account the appropriate spherically averaged density profile of haloes for each DM model. We treat the lensing system as a point-mass lens and invoke the effective surface mass density threshold to calculate the fraction of a halo that acts as a gravitational lens. We study three classes of dark matter models: cold DM, warm DM, and self-interacting DM. We find that haloes consisting of warm DM turn out to be optically thin for strong gravitational milli-lensing (zero expected lensing events). CDM haloes may produce lensing events depending on the steepness of the concentration-mass relation. Self-interacting DM haloes can efficiently act as gravitational milli-lenses only if haloes experience gravothermal collapse, resulting in highly dense central cores. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.13393v1-abstract-full').style.display = 'none'; document.getElementById('2209.13393v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 September, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 6 figures. Submitted for publication in A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 668, A166 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2209.06227">arXiv:2209.06227</a> <span> [<a href="https://arxiv.org/pdf/2209.06227">pdf</a>, <a href="https://arxiv.org/format/2209.06227">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41586-022-05338-0">10.1038/s41586-022-05338-0 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Polarized Blazar X-rays imply particle acceleration in shocks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Berdyugin%2C+A+V">Andrei V. Berdyugin</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardos%2C+M+I">Maria I. Bernardos</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">Giacomo Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Borman%2C+G+A">George A. Borman</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">Carolina Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Casanova%2C+V">V铆ctor Casanova</a>, <a href="/search/astro-ph?searchtype=author&query=Cavazzuti%2C+E">Elisabetta Cavazzuti</a>, <a href="/search/astro-ph?searchtype=author&query=Cavero%2C+N+R">Nicole Rodriguez Cavero</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Lalla%2C+N">Niccol贸 Di Lalla</a>, <a href="/search/astro-ph?searchtype=author&query=Donnarumma%2C+I">Immacolata Donnarumma</a>, <a href="/search/astro-ph?searchtype=author&query=Ehlert%2C+S+R">Steven R. Ehlert</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Escudero%2C+J">Juan Escudero</a>, <a href="/search/astro-ph?searchtype=author&query=Garc%C3%ADa-Comas%2C+M">Maya Garc铆a-Comas</a>, <a href="/search/astro-ph?searchtype=author&query=Ag%C3%ADs-Gonz%C3%A1lez%2C+B">Beatriz Ag铆s-Gonz谩lez</a>, <a href="/search/astro-ph?searchtype=author&query=Husillos%2C+C">C茅sar Husillos</a>, <a href="/search/astro-ph?searchtype=author&query=Jormanainen%2C+J">Jenni Jormanainen</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Kagitani%2C+M">Masato Kagitani</a>, <a href="/search/astro-ph?searchtype=author&query=Kopatskaya%2C+E+N">Evgenia N. Kopatskaya</a>, <a href="/search/astro-ph?searchtype=author&query=Kravtsov%2C+V">Vadim Kravtsov</a> , et al. (103 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2209.06227v2-abstract-short" style="display: inline;"> Most of the light from blazars, active galactic nuclei with jets of magnetized plasma that point nearly along the line of sight, is produced by high-energy particles, up to $\sim 1$ TeV. Although the jets are known to be ultimately powered by a supermassive black hole, how the particles are accelerated to such high energies has been an unanswered question. The process must be related to the magnet… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.06227v2-abstract-full').style.display = 'inline'; document.getElementById('2209.06227v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2209.06227v2-abstract-full" style="display: none;"> Most of the light from blazars, active galactic nuclei with jets of magnetized plasma that point nearly along the line of sight, is produced by high-energy particles, up to $\sim 1$ TeV. Although the jets are known to be ultimately powered by a supermassive black hole, how the particles are accelerated to such high energies has been an unanswered question. The process must be related to the magnetic field, which can be probed by observations of the polarization of light from the jets. Measurements of the radio to optical polarization - the only range available until now - probe extended regions of the jet containing particles that left the acceleration site days to years earlier (Jorstad et al., 2005; Marin et al., 2018; Blinov et al., 2021), and hence do not directly explore the acceleration mechanism, as could X-ray measurements. Here we report the detection of X-ray polarization from the blazar Markarian~501 (Mrk~501). We measure an X-ray linear polarization degree $螤_X \sim10\%$, a factor of $\sim2$ higher than the value at optical wavelengths, with a polarization angle parallel to the radio jet. This points to a shock front as the source of particle acceleration, and also implies that the plasma becomes increasingly turbulent with distance from the shock. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.06227v2-abstract-full').style.display = 'none'; document.getElementById('2209.06227v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 September, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">34 pages, 4 figures, 4 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> 2022, Nature, 611, 677-681 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2208.12441">arXiv:2208.12441</a> <span> [<a href="https://arxiv.org/pdf/2208.12441">pdf</a>, <a href="https://arxiv.org/format/2208.12441">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1117/1.JATIS.8.3.038004">10.1117/1.JATIS.8.3.038004 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> WALOP-South: A Four-Camera One-Shot Imaging Polarimeter for PASIPHAE Survey. Paper II -- Polarimetric Modelling and Calibration </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Maharana%2C+S">Siddharth Maharana</a>, <a href="/search/astro-ph?searchtype=author&query=Anche%2C+R+M">Ramya M. Anche</a>, <a href="/search/astro-ph?searchtype=author&query=Ramaprakash%2C+A+N">A. N. Ramaprakash</a>, <a href="/search/astro-ph?searchtype=author&query=Joshi%2C+B">Bhushan Joshi</a>, <a href="/search/astro-ph?searchtype=author&query=Basyrov%2C+A">Artem Basyrov</a>, <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D">Dmitry Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">Carolina Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Deka%2C+K">Kishan Deka</a>, <a href="/search/astro-ph?searchtype=author&query=Eriksen%2C+H+K">Hans Kristian Eriksen</a>, <a href="/search/astro-ph?searchtype=author&query=Ghosh%2C+T">Tuhin Ghosh</a>, <a href="/search/astro-ph?searchtype=author&query=Gjerl%C3%B8w%2C+E">Eirik Gjerl酶w</a>, <a href="/search/astro-ph?searchtype=author&query=Kypriotakis%2C+J+A">John A. Kypriotakis</a>, <a href="/search/astro-ph?searchtype=author&query=Kiehlmann%2C+S">Sebastian Kiehlmann</a>, <a href="/search/astro-ph?searchtype=author&query=Mandarakas%2C+N">Nikolaos Mandarakas</a>, <a href="/search/astro-ph?searchtype=author&query=Panopoulou%2C+G+V">Georgia V. Panopoulou</a>, <a href="/search/astro-ph?searchtype=author&query=Papadaki%2C+K">Katerina Papadaki</a>, <a href="/search/astro-ph?searchtype=author&query=Pavlidou%2C+V">Vasiliki Pavlidou</a>, <a href="/search/astro-ph?searchtype=author&query=Pearson%2C+T+J">Timothy J. Pearson</a>, <a href="/search/astro-ph?searchtype=author&query=Pelgrims%2C+V">Vincent Pelgrims</a>, <a href="/search/astro-ph?searchtype=author&query=Potter%2C+S+B">Stephen B. Potter</a>, <a href="/search/astro-ph?searchtype=author&query=Readhead%2C+A+C+S">Anthony C. S. Readhead</a>, <a href="/search/astro-ph?searchtype=author&query=Skalidis%2C+R">Raphael Skalidis</a>, <a href="/search/astro-ph?searchtype=author&query=Svalheim%2C+T+L">Trygve Leithe Svalheim</a>, <a href="/search/astro-ph?searchtype=author&query=Tassis%2C+K">Konstantinos Tassis</a>, <a href="/search/astro-ph?searchtype=author&query=Wehus%2C+I+K">Ingunn K. Wehus</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2208.12441v1-abstract-short" style="display: inline;"> The Wide-Area Linear Optical Polarimeter (WALOP)-South instrument is an upcoming wide-field and high-accuracy optical polarimeter to be used as a survey instrument for carrying out the Polar-Areas Stellar Imaging in Polarization High Accuracy Experiment (PASIPHAE) program. Designed to operate as a one-shot four-channel and four-camera imaging polarimeter, it will have a field of view of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.12441v1-abstract-full').style.display = 'inline'; document.getElementById('2208.12441v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2208.12441v1-abstract-full" style="display: none;"> The Wide-Area Linear Optical Polarimeter (WALOP)-South instrument is an upcoming wide-field and high-accuracy optical polarimeter to be used as a survey instrument for carrying out the Polar-Areas Stellar Imaging in Polarization High Accuracy Experiment (PASIPHAE) program. Designed to operate as a one-shot four-channel and four-camera imaging polarimeter, it will have a field of view of $35\times 35$ arcminutes and will measure the Stokes parameters $I$, $q$, and $u$ in a single exposure in the SDSS-r broadband filter. The design goal for the instrument is to achieve an overall polarimetric measurement accuracy of 0.1 % over the entire field of view. We present here the complete polarimetric modeling of the instrument, characterizing the amount and sources of instrumental polarization. To accurately retrieve the real Stokes parameters of a source from the measured values, we have developed a calibration method for the instrument. Using this calibration method and simulated data, we demonstrate how to correct instrumental polarization and obtain 0.1 % accuracy in the degree of polarization, $p$. Additionally, we tested and validated the calibration method by implementing it on a table-top WALOP-like test-bed polarimeter in the laboratory. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.12441v1-abstract-full').style.display = 'none'; document.getElementById('2208.12441v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 August, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">34 pages, 24 figures. Accepted for publication in the Journal of Astronomical Telescopes, Instruments, and Systems</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> J. of Astronomical Telescopes, Instruments, and Systems, 8(3), 038004 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2202.02523">arXiv:2202.02523</a> <span> [<a href="https://arxiv.org/pdf/2202.02523">pdf</a>, <a href="https://arxiv.org/format/2202.02523">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202142948">10.1051/0004-6361/202142948 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> New jet feature in the parsec-scale jet of the blazar OJ287 connected to the 2017 teraelectronvolt flaring activity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Lico%2C+R">R. Lico</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">C. Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">S. G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Gomez%2C+J+L">J. L. Gomez</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">A. P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Traianou%2C+E">E. Traianou</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+J+Y">J. Y. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Zhao%2C+G+Y">G. Y. Zhao</a>, <a href="/search/astro-ph?searchtype=author&query=Fuentes%2C+A">A. Fuentes</a>, <a href="/search/astro-ph?searchtype=author&query=Cho%2C+I">I. Cho</a>, <a href="/search/astro-ph?searchtype=author&query=Krichbaum%2C+T+P">T. P. Krichbaum</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">O. Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=O%27Brien%2C+S">S. O'Brien</a>, <a href="/search/astro-ph?searchtype=author&query=Boccardi%2C+B">B. Boccardi</a>, <a href="/search/astro-ph?searchtype=author&query=Myserlis%2C+I">I. Myserlis</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">I. Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Alberdi%2C+A">A. Alberdi</a>, <a href="/search/astro-ph?searchtype=author&query=Weaver%2C+Z+R">Z. R. Weaver</a>, <a href="/search/astro-ph?searchtype=author&query=Zensus%2C+J+A">J. A. Zensus</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2202.02523v2-abstract-short" style="display: inline;"> In February 2017 the blazar OJ287, one of the best super-massive binary-black-hole-system candidates, was detected for the first time at very high energies (VHEs; E>100GeV) with the ground-based gamma-ray observatory VERITAS. Very high energy gamma rays are thought to be produced in the near vicinity of the central engine in active galactic nuclei. For this reason, and with the main goal of provid… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.02523v2-abstract-full').style.display = 'inline'; document.getElementById('2202.02523v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2202.02523v2-abstract-full" style="display: none;"> In February 2017 the blazar OJ287, one of the best super-massive binary-black-hole-system candidates, was detected for the first time at very high energies (VHEs; E>100GeV) with the ground-based gamma-ray observatory VERITAS. Very high energy gamma rays are thought to be produced in the near vicinity of the central engine in active galactic nuclei. For this reason, and with the main goal of providing useful information for the characterization of the physical mechanisms connected with the observed teraelectronvolt flaring event, we investigate the parsec-scale source properties by means of high-resolution very long baseline interferometry observations. We use 86 GHz Global Millimeter-VLBI Array (GMVA) observations from 2015 to 2017 and combine them with additional multiwavelength radio observations at different frequencies from other monitoring programs. We investigate the source structure by modeling the brightness distribution with two-dimensional Gaussian components in the visibility plane. In the GMVA epoch following the source VHE activity, we find a new jet feature (labeled K) at about 0.2 mas from the core region and located in between two quasi-stationary components (labeled S1 and S2). Multiple periods of enhanced activity are detected at different radio frequencies before and during the VHE flaring state. Based on the findings of this work, we identify as a possible trigger for the VHE flaring emission during the early months of 2017 the passage of a new jet feature through a recollimation shock (represented by the model-fit component S1) in a region of the jet located at a de-projected distance of about 10 pc from the radio core. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.02523v2-abstract-full').style.display = 'none'; document.getElementById('2202.02523v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 February, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 February, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 3 figure, 1 table</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 658, L10 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2202.00061">arXiv:2202.00061</a> <span> [<a href="https://arxiv.org/pdf/2202.00061">pdf</a>, <a href="https://arxiv.org/format/2202.00061">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ac4710">10.3847/1538-4357/ac4710 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Emission Line Variability during a Nonthermal Outburst in the Gamma-Ray Bright Quasar 1156+295 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Hallum%2C+M+K">Melissa K. Hallum</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Larionov%2C+V+M">Valeri M. Larionov</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Joshi%2C+M">Manasvita Joshi</a>, <a href="/search/astro-ph?searchtype=author&query=Weaver%2C+Z+R">Zachary R. Weaver</a>, <a href="/search/astro-ph?searchtype=author&query=Williamson%2C+K+E">Karen E. Williamson</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Ivan Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Borman%2C+G+A">George A. Borman</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">Carolina Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Fuentes%2C+A">Antonio Fuentes</a>, <a href="/search/astro-ph?searchtype=author&query=Grishina%2C+T+S">Tatiana S. Grishina</a>, <a href="/search/astro-ph?searchtype=author&query=Kopatskaya%2C+E+N">Evgenia N. Kopatskaya</a>, <a href="/search/astro-ph?searchtype=author&query=Larionova%2C+E+G">Elena G. Larionova</a>, <a href="/search/astro-ph?searchtype=author&query=Larionova%2C+L+V">Liyudmila V. Larionova</a>, <a href="/search/astro-ph?searchtype=author&query=Morozova%2C+D+A">Daria A. Morozova</a>, <a href="/search/astro-ph?searchtype=author&query=Nikiforova%2C+A+A">Anna A. Nikiforova</a>, <a href="/search/astro-ph?searchtype=author&query=Savchenko%2C+S+S">Sergey S. Savchenko</a>, <a href="/search/astro-ph?searchtype=author&query=Troitsky%2C+I+S">Ivan S. Troitsky</a>, <a href="/search/astro-ph?searchtype=author&query=Troitskaya%2C+Y+V">Yulia V. Troitskaya</a>, <a href="/search/astro-ph?searchtype=author&query=Vasilyev%2C+A+A">Andrey A. Vasilyev</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2202.00061v1-abstract-short" style="display: inline;"> We present multi-epoch optical spectra of the $纬$-ray bright blazar 1156+295 (4C +29.45, Ton 599) obtained with the 4.3~m Lowell Discovery Telescope. During a multi-wavelength outburst in late 2017, when the $纬$-ray flux increased to $2.5\times 10^{-6} \; \rm phot\; cm^{-2}\; s^{-1}$ and the quasar was first detected at energies $\geq100$ GeV, the flux of the Mg II $位2798$ emission line changed, a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.00061v1-abstract-full').style.display = 'inline'; document.getElementById('2202.00061v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2202.00061v1-abstract-full" style="display: none;"> We present multi-epoch optical spectra of the $纬$-ray bright blazar 1156+295 (4C +29.45, Ton 599) obtained with the 4.3~m Lowell Discovery Telescope. During a multi-wavelength outburst in late 2017, when the $纬$-ray flux increased to $2.5\times 10^{-6} \; \rm phot\; cm^{-2}\; s^{-1}$ and the quasar was first detected at energies $\geq100$ GeV, the flux of the Mg II $位2798$ emission line changed, as did that of the Fe emission complex at shorter wavelengths. These emission line fluxes increased along with the highly polarized optical continuum flux, which is presumably synchrotron radiation from the relativistic jet, with a relative time delay of $\lesssim2$ weeks. This implies that the line-emitting clouds lie near the jet, which points almost directly toward the line of sight. The emission-line radiation from such clouds, which are located outside the canonical accretion-disk related broad-line region, may be a primary source of seed photons that are up-scattered to $纬$-ray energies by relativistic electrons in the jet. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.00061v1-abstract-full').style.display = 'none'; document.getElementById('2202.00061v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 31 January, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">25 pages, 12 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> 2022 ApJ 926 180 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2111.11200">arXiv:2111.11200</a> <span> [<a href="https://arxiv.org/pdf/2111.11200">pdf</a>, <a href="https://arxiv.org/format/2111.11200">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ac3bcc">10.3847/1538-4357/ac3bcc <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Probing the innermost regions of AGN jets and their magnetic fields with RadioAstron. V. Space and ground millimeter-VLBI imaging of OJ 287 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=G%C3%B3mez%2C+J+L">Jose L. G贸mez</a>, <a href="/search/astro-ph?searchtype=author&query=Traianou%2C+E">Efthalia Traianou</a>, <a href="/search/astro-ph?searchtype=author&query=Krichbaum%2C+T+P">Thomas P. Krichbaum</a>, <a href="/search/astro-ph?searchtype=author&query=Lobanov%2C+A">Andrei Lobanov</a>, <a href="/search/astro-ph?searchtype=author&query=Fuentes%2C+A">Antonio Fuentes</a>, <a href="/search/astro-ph?searchtype=author&query=Lico%2C+R">Rocco Lico</a>, <a href="/search/astro-ph?searchtype=author&query=Zhao%2C+G">Guang-Yao Zhao</a>, <a href="/search/astro-ph?searchtype=author&query=Bruni%2C+G">Gabriele Bruni</a>, <a href="/search/astro-ph?searchtype=author&query=Kovalev%2C+Y+Y">Yuri Y. Kovalev</a>, <a href="/search/astro-ph?searchtype=author&query=Lahteenmaki%2C+A">Anne Lahteenmaki</a>, <a href="/search/astro-ph?searchtype=author&query=Voitsik%2C+P+A">Petr A. Voitsik</a>, <a href="/search/astro-ph?searchtype=author&query=Lisakov%2C+M+M">Mikhail M. Lisakov</a>, <a href="/search/astro-ph?searchtype=author&query=Angelakis%2C+E">Emmanouil Angelakis</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">Uwe Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">Carolina Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Cho%2C+I">Ilje Cho</a>, <a href="/search/astro-ph?searchtype=author&query=Dey%2C+L">Lankeswar Dey</a>, <a href="/search/astro-ph?searchtype=author&query=Gopakumar%2C+A">Achamveedu Gopakumar</a>, <a href="/search/astro-ph?searchtype=author&query=Gurvits%2C+L">Leonid Gurvits</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Kovalev%2C+Y+A">Yuri A. Kovalev</a>, <a href="/search/astro-ph?searchtype=author&query=Lister%2C+M+L">Matthew L. Lister</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Myserlis%2C+I">Ioannis Myserlis</a>, <a href="/search/astro-ph?searchtype=author&query=Pushkarev%2C+A">Alexander Pushkarev</a> , et al. (5 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2111.11200v2-abstract-short" style="display: inline;"> We present the first polarimetric space VLBI observations of OJ 287, observed with RadioAstron at 22 GHz during a perigee session on 2014 April 4 and five near-in-time snapshots, together with contemporaneous ground VLBI observations at 15, 43, and 86 GHz. Ground-space fringes were obtained up to a projected baseline of 3.9 Earth diameters during the perigee session, and at a record 15.1 Earth dia… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.11200v2-abstract-full').style.display = 'inline'; document.getElementById('2111.11200v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2111.11200v2-abstract-full" style="display: none;"> We present the first polarimetric space VLBI observations of OJ 287, observed with RadioAstron at 22 GHz during a perigee session on 2014 April 4 and five near-in-time snapshots, together with contemporaneous ground VLBI observations at 15, 43, and 86 GHz. Ground-space fringes were obtained up to a projected baseline of 3.9 Earth diameters during the perigee session, and at a record 15.1 Earth diameters during the snapshot sessions, allowing us to image the innermost jet at an angular resolution of $\sim50渭$as, the highest ever achieved at 22 GHz for OJ 287. Comparison with ground-based VLBI observations reveals a progressive jet bending with increasing angular resolution that agrees with predictions from a supermassive binary black hole model, although other models cannot be ruled out. Spectral analyses suggest that the VLBI core is dominated by the internal energy of the emitting particles during the onset of a multi-wavelength flare, while the parsec-scale jet is consistent with being in equipartition between the particles and magnetic field. Estimated minimum brightness temperatures from the visibility amplitudes show a continued rising trend with projected baseline length up to $10^{13}$ K, reconciled with the inverse Compton limit through Doppler boosting for a jet closely oriented to the line of sight. The observed electric vector position angle suggests that the innermost jet has a predominantly toroidal magnetic field, which together with marginal evidence of a gradient in rotation measure across the jet width indicate that the VLBI core is threaded by a helical magnetic field, in agreement with jet formation models. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.11200v2-abstract-full').style.display = 'none'; document.getElementById('2111.11200v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 November, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 November, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJ 924 (2022) 122 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2107.06896">arXiv:2107.06896</a> <span> [<a href="https://arxiv.org/pdf/2107.06896">pdf</a>, <a href="https://arxiv.org/format/2107.06896">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnrasl/slab082">10.1093/mnrasl/slab082 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> SMILE: Search for MIlli-LEnses </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">C. Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D">D. Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Readhead%2C+A+C+S">A. C. S. Readhead</a>, <a href="/search/astro-ph?searchtype=author&query=Browne%2C+I+W+A">I. W. A. Browne</a>, <a href="/search/astro-ph?searchtype=author&query=Wilkinson%2C+P+N">P. N. Wilkinson</a>, <a href="/search/astro-ph?searchtype=author&query=Hovatta%2C+T">T. Hovatta</a>, <a href="/search/astro-ph?searchtype=author&query=Mandarakas%2C+N">N. Mandarakas</a>, <a href="/search/astro-ph?searchtype=author&query=Pavlidou%2C+V">V. Pavlidou</a>, <a href="/search/astro-ph?searchtype=author&query=Tassis%2C+K">K. Tassis</a>, <a href="/search/astro-ph?searchtype=author&query=Vedantham%2C+H+K">H. K. Vedantham</a>, <a href="/search/astro-ph?searchtype=author&query=Zensus%2C+J+A">J. A. Zensus</a>, <a href="/search/astro-ph?searchtype=author&query=Diamantopoulos%2C+V">V. Diamantopoulos</a>, <a href="/search/astro-ph?searchtype=author&query=Dolapsaki%2C+K+E">K. E. Dolapsaki</a>, <a href="/search/astro-ph?searchtype=author&query=Gkimisi%2C+K">K. Gkimisi</a>, <a href="/search/astro-ph?searchtype=author&query=Kalaitzidakis%2C+G">G. Kalaitzidakis</a>, <a href="/search/astro-ph?searchtype=author&query=Mastorakis%2C+M">M. Mastorakis</a>, <a href="/search/astro-ph?searchtype=author&query=Nikolaou%2C+K">K. Nikolaou</a>, <a href="/search/astro-ph?searchtype=author&query=Ntormousi%2C+E">E. Ntormousi</a>, <a href="/search/astro-ph?searchtype=author&query=Pelgrims%2C+V">V. Pelgrims</a>, <a href="/search/astro-ph?searchtype=author&query=Psarras%2C+K">K. Psarras</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2107.06896v1-abstract-short" style="display: inline;"> Dark Matter (DM) halos with masses below $\sim10^{8}$ $M_{\odot}$, which would help to discriminate between DM models, may be detected through their gravitational effect on distant sources. The same applies to primordial black holes, considered as an alternative scenario to DM particle models. However, there is still no evidence for the existence of such objects. With the aim of finding compact ob… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.06896v1-abstract-full').style.display = 'inline'; document.getElementById('2107.06896v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2107.06896v1-abstract-full" style="display: none;"> Dark Matter (DM) halos with masses below $\sim10^{8}$ $M_{\odot}$, which would help to discriminate between DM models, may be detected through their gravitational effect on distant sources. The same applies to primordial black holes, considered as an alternative scenario to DM particle models. However, there is still no evidence for the existence of such objects. With the aim of finding compact objects in the mass range $\sim$ 10$^{6}$ -- 10$^{9}$$M_{\odot}$, we search for strong gravitational lenses on milli (mas)-arcseconds scales (< 150 mas). For our search, we used the Astrogeo VLBI FITS image database -- the largest publicly available database, containing multi-frequency VLBI data of 13828 individual sources. We used the citizen science approach to visually inspect all sources in all available frequencies in search for images with multiple compact components on mas-scales. At the final stage, sources were excluded based on the surface brightness preservation criterion. We obtained a sample of 40 sources that passed all steps and therefore are judged to be milli-arcsecond lens candidates. These sources are currently followed-up with on-going European VLBI Network (EVN) observations at 5 and 22 GHz. Based on spectral index measurements, we suggest that two of our candidates have a higher probability to be associated with gravitational lenses. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.06896v1-abstract-full').style.display = 'none'; document.getElementById('2107.06896v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 July, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 1 figure; accepted for publication</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2106.06546">arXiv:2106.06546</a> <span> [<a href="https://arxiv.org/pdf/2106.06546">pdf</a>, <a href="https://arxiv.org/format/2106.06546">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202140764">10.1051/0004-6361/202140764 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Local alignments of parsec-scale AGN radiojets </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Mandarakas%2C+N">N. Mandarakas</a>, <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D">D. Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">C. Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Pelgrims%2C+V">V. Pelgrims</a>, <a href="/search/astro-ph?searchtype=author&query=Kiehlmann%2C+S">S. Kiehlmann</a>, <a href="/search/astro-ph?searchtype=author&query=Pavlidou%2C+V">V. Pavlidou</a>, <a href="/search/astro-ph?searchtype=author&query=Tassis%2C+K">K. Tassis</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2106.06546v1-abstract-short" style="display: inline;"> Context.Coherence in the characteristics of neighboring sources in 2D and 3D space may suggest the existence of large-scale cosmic structures, which are useful for cosmological studies. Numerous works have been conducted to detect such features in global scalesas well as in confined areas of the sky. However, results are often contradictory and their interpretation remains controversial. Aims.We i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.06546v1-abstract-full').style.display = 'inline'; document.getElementById('2106.06546v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2106.06546v1-abstract-full" style="display: none;"> Context.Coherence in the characteristics of neighboring sources in 2D and 3D space may suggest the existence of large-scale cosmic structures, which are useful for cosmological studies. Numerous works have been conducted to detect such features in global scalesas well as in confined areas of the sky. However, results are often contradictory and their interpretation remains controversial. Aims.We investigate the potential alignment of parsec-scale radio jets in localized regions of the coordinates-redshift space. Methods.We use data from the Astrogeo VLBI FITS image database to deduce jet directions of radio sources. We perform the search for statistical alignments between nearby sources and explore the impact of instrumental biases. Results.We unveil four regions for which the alignment between jet directions deviates from randomness at a significance level of more than 5 sigma and is unlikely due to instrumental systematics. Intriguingly, their locations coincide with other known large-scale cosmic structures and/or regions of alignments. Conclusions.If the alignments found are the result of physical processes, the discovered regions may designate some of the largest structures known to date. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.06546v1-abstract-full').style.display = 'none'; document.getElementById('2106.06546v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 June, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 9 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 653, A123 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2106.05516">arXiv:2106.05516</a> <span> [<a href="https://arxiv.org/pdf/2106.05516">pdf</a>, <a href="https://arxiv.org/format/2106.05516">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202141004">10.1051/0004-6361/202141004 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Investigation of the correlation patterns and the Compton dominance variability of Mrk 421 in 2017 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=MAGIC+Collaboration"> MAGIC Collaboration</a>, <a href="/search/astro-ph?searchtype=author&query=Acciari%2C+V+A">V. A. Acciari</a>, <a href="/search/astro-ph?searchtype=author&query=Ansoldi%2C+S">S. Ansoldi</a>, <a href="/search/astro-ph?searchtype=author&query=Antonelli%2C+L+A">L. A. Antonelli</a>, <a href="/search/astro-ph?searchtype=author&query=Engels%2C+A+A">A. Arbet Engels</a>, <a href="/search/astro-ph?searchtype=author&query=Artero%2C+M">M. Artero</a>, <a href="/search/astro-ph?searchtype=author&query=Asano%2C+K">K. Asano</a>, <a href="/search/astro-ph?searchtype=author&query=Babi%C4%87%2C+A">A. Babi膰</a>, <a href="/search/astro-ph?searchtype=author&query=Baquero%2C+A">A. Baquero</a>, <a href="/search/astro-ph?searchtype=author&query=de+Almeida%2C+U+B">U. Barres de Almeida</a>, <a href="/search/astro-ph?searchtype=author&query=Barrio%2C+J+A">J. A. Barrio</a>, <a href="/search/astro-ph?searchtype=author&query=Batkovi%C4%87%2C+I">I. Batkovi膰</a>, <a href="/search/astro-ph?searchtype=author&query=Gonz%C3%A1lez%2C+J+B">J. Becerra Gonz谩lez</a>, <a href="/search/astro-ph?searchtype=author&query=Bednarek%2C+W">W. Bednarek</a>, <a href="/search/astro-ph?searchtype=author&query=Bellizzi%2C+L">L. Bellizzi</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardini%2C+E">E. Bernardini</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardos%2C+M">M. Bernardos</a>, <a href="/search/astro-ph?searchtype=author&query=Berti%2C+A">A. Berti</a>, <a href="/search/astro-ph?searchtype=author&query=Besenrieder%2C+J">J. Besenrieder</a>, <a href="/search/astro-ph?searchtype=author&query=Bhattacharyya%2C+W">W. Bhattacharyya</a>, <a href="/search/astro-ph?searchtype=author&query=Bigongiari%2C+C">C. Bigongiari</a>, <a href="/search/astro-ph?searchtype=author&query=Blanch%2C+O">O. Blanch</a>, <a href="/search/astro-ph?searchtype=author&query=Bo%C5%A1njak%2C+%C5%BD">沤. Bo拧njak</a>, <a href="/search/astro-ph?searchtype=author&query=Busetto%2C+G">G. Busetto</a>, <a href="/search/astro-ph?searchtype=author&query=Carosi%2C+R">R. Carosi</a> , et al. (263 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2106.05516v1-abstract-short" style="display: inline;"> We present a detailed characterisation and theoretical interpretation of the broadband emission of the paradigmatic TeV blazar Mrk 421, with special focus on the multi-band flux correlations. The dataset has been collected through an extensive multiwavelength campaign organised between 2016 December and 2017 June. The instruments involved are MAGIC, FACT, Fermi-LAT, Swift, GASP-WEBT, OVRO, Medicin… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.05516v1-abstract-full').style.display = 'inline'; document.getElementById('2106.05516v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2106.05516v1-abstract-full" style="display: none;"> We present a detailed characterisation and theoretical interpretation of the broadband emission of the paradigmatic TeV blazar Mrk 421, with special focus on the multi-band flux correlations. The dataset has been collected through an extensive multiwavelength campaign organised between 2016 December and 2017 June. The instruments involved are MAGIC, FACT, Fermi-LAT, Swift, GASP-WEBT, OVRO, Medicina and Mets盲hovi. Additionally, four deep exposures (several hours long) with simultaneous MAGIC and NuSTAR observations allowed a precise measurement of the falling segments of the two spectral components. The very-high-energy (VHE; E > 100 GeV) gamma rays and X-rays are positively correlated at zero time lag, but the strength and characteristics of the correlation change substantially across the various energy bands probed. The VHE versus X-ray fluxes follow different patterns, partly due to substantial changes in the Compton dominance during a few days without a simultaneous increase in the X-ray flux (i.e. orphan gamma-ray activity). Studying the broadband spectral energy distribution (SED) during the days including NuSTAR observations, we show that these changes can be explained within a one-zone leptonic model with a blob that increases its size over time. Our multi-band correlation study also hints at an anti-correlation between UV/optical and X-ray at a significance higher than 3 sigmas. A VHE flare observed on 2017 February 4 shows gamma-ray variability on multi-hour timescales, with a factor 10 increase in the TeV flux but only a moderate increase in the keV flux. The related broadband SED is better described by a two-zone leptonic scenario rather than by a one-zone scenario. We find that the flare can be produced by the appearance of a compact second blob populated by high energetic electrons spanning a narrow range of Lorentz factors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.05516v1-abstract-full').style.display = 'none'; document.getElementById('2106.05516v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 June, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">38 pages, 23 figures, accepted for publication in Astronomy and Astrophysics. Corresponding authors: Axel Arbet-Engels, David Paneque</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 655, A89 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2104.02622">arXiv:2104.02622</a> <span> [<a href="https://arxiv.org/pdf/2104.02622">pdf</a>, <a href="https://arxiv.org/format/2104.02622">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stab2055">10.1093/mnras/stab2055 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Time-Dependent Distribution of Optical Polarization Angle Changes in Blazars </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kiehlmann%2C+S">S. Kiehlmann</a>, <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D">D. Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">I. Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Pavlidou%2C+V">V. Pavlidou</a>, <a href="/search/astro-ph?searchtype=author&query=Readhead%2C+A+C+S">A. C. S. Readhead</a>, <a href="/search/astro-ph?searchtype=author&query=Angelakis%2C+E">E. Angelakis</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">C. Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Hovatta%2C+T">T. Hovatta</a>, <a href="/search/astro-ph?searchtype=author&query=Kylafis%2C+N">N. Kylafis</a>, <a href="/search/astro-ph?searchtype=author&query=Mahabal%2C+A">A. Mahabal</a>, <a href="/search/astro-ph?searchtype=author&query=Mandarakas%2C+N">N. Mandarakas</a>, <a href="/search/astro-ph?searchtype=author&query=Myserlis%2C+I">I. Myserlis</a>, <a href="/search/astro-ph?searchtype=author&query=Panopoulou%2C+G+V">G. V. Panopoulou</a>, <a href="/search/astro-ph?searchtype=author&query=Pearson%2C+T+J">T. J. Pearson</a>, <a href="/search/astro-ph?searchtype=author&query=Ramaprakash%2C+A">A. Ramaprakash</a>, <a href="/search/astro-ph?searchtype=author&query=Reig%2C+P">P. Reig</a>, <a href="/search/astro-ph?searchtype=author&query=Skalidis%2C+R">R. Skalidis</a>, <a href="/search/astro-ph?searchtype=author&query=Slowikowska%2C+A">A. Slowikowska</a>, <a href="/search/astro-ph?searchtype=author&query=Tassis%2C+K">K. Tassis</a>, <a href="/search/astro-ph?searchtype=author&query=Zensus%2C+J+A">J. A. Zensus</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2104.02622v2-abstract-short" style="display: inline;"> At optical wavelengths, blazar Electric Vector Position Angle (EVPA) rotations linked with gamma-ray activity have been the subject of intense interest and systematic investigation for over a decade. One difficulty in the interpretation of EVPA rotations is the inherent 180掳 ambiguity in the measurements. It is therefore essential, when studying EVPA rotations, to ensure that the typical time-inte… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.02622v2-abstract-full').style.display = 'inline'; document.getElementById('2104.02622v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2104.02622v2-abstract-full" style="display: none;"> At optical wavelengths, blazar Electric Vector Position Angle (EVPA) rotations linked with gamma-ray activity have been the subject of intense interest and systematic investigation for over a decade. One difficulty in the interpretation of EVPA rotations is the inherent 180掳 ambiguity in the measurements. It is therefore essential, when studying EVPA rotations, to ensure that the typical time-interval between successive observations -- i.e. the cadence -- is short enough to ensure that the correct modulo 180掳 value is selected. This optimal cadence depends on the maximum intrinsic EVPA rotation speed in blazars, which is currently not known. In this paper we address the following questions for the RoboPol sample: What range of rotation speeds for rotations greater than 90掳 can we expect? What observation cadence is required to detect such rotations? Have rapid rotations been missed in EVPA rotation studies thus far? What fraction of data is affected by the ambiguity? And how likely are detected rotations affected by the ambiguity? We answer these questions with three seasons of optical polarimetric observations of a statistical sample of blazars sampled weekly with the RoboPol instrument and an additional season with daily observations. We model the distribution of EVPA changes on time scales from 1-30 days and estimate the fraction of changes exceeding 90掳. We show that at least daily observations are necessary to measure >96% of optical EVPA variability in the RoboPol sample of blazars correctly and that intra-day observations are needed to measure the fastest rotations that have been seen thus far. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.02622v2-abstract-full').style.display = 'none'; document.getElementById('2104.02622v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 July, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 April, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">accepted to MNRAS, 20 pages, 15 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2102.08952">arXiv:2102.08952</a> <span> [<a href="https://arxiv.org/pdf/2102.08952">pdf</a>, <a href="https://arxiv.org/format/2102.08952">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202039616">10.1051/0004-6361/202039616 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The jet collimation profile at high resolution in BL Lacertae </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">C. Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=MacDonald%2C+N+R">N. R. MacDonald</a>, <a href="/search/astro-ph?searchtype=author&query=Boccardi%2C+B">B. Boccardi</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">S. G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">A. P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Krichbaum%2C+T+P">T. P. Krichbaum</a>, <a href="/search/astro-ph?searchtype=author&query=Hodgson%2C+J+A">J. A. Hodgson</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+J">J-Y. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Traianou%2C+E">E. Traianou</a>, <a href="/search/astro-ph?searchtype=author&query=Weaver%2C+Z+R">Z. R. Weaver</a>, <a href="/search/astro-ph?searchtype=author&query=Garrido%2C+M+G">M. G贸mez Garrido</a>, <a href="/search/astro-ph?searchtype=author&query=Garc%C3%ADa%2C+J+G">J. Gonz谩lez Garc铆a</a>, <a href="/search/astro-ph?searchtype=author&query=Kallunki%2C+J">J. Kallunki</a>, <a href="/search/astro-ph?searchtype=author&query=Lindqvist%2C+M">M. Lindqvist</a>, <a href="/search/astro-ph?searchtype=author&query=S%C3%A1nchez%2C+S">S. S谩nchez</a>, <a href="/search/astro-ph?searchtype=author&query=Yang%2C+J">J. Yang</a>, <a href="/search/astro-ph?searchtype=author&query=Zensus%2C+J+A">J. A. Zensus</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2102.08952v2-abstract-short" style="display: inline;"> Controversial studies on the jet collimation profile of BL Lacertae (BL Lac), the eponymous blazar of BL Lac objects class, complicate the scenario in this already puzzling class of objects. Understanding the jet geometry, in connection with the jet kinematics and the physical conditions in the surrounding medium, is fundamental to better constrain the formation, acceleration and collimation mecha… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.08952v2-abstract-full').style.display = 'inline'; document.getElementById('2102.08952v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2102.08952v2-abstract-full" style="display: none;"> Controversial studies on the jet collimation profile of BL Lacertae (BL Lac), the eponymous blazar of BL Lac objects class, complicate the scenario in this already puzzling class of objects. Understanding the jet geometry, in connection with the jet kinematics and the physical conditions in the surrounding medium, is fundamental to better constrain the formation, acceleration and collimation mechanisms in extragalactic jets. With the aim of investigating the jet geometry in the innermost regions of the jet of BL Lac, and solving the controversy, we explore the radio jet in this source, using high resolution millimeter-wave VLBI data. We collect 86GHz GMVA and 43GHz VLBA data to obtain stacked images that we use to infer the jet collimation profile by means of two comparable methods. We analyze the kinematics at 86GHz, and we discuss it in the context of the jet expansion. Finally we consider a possible implication of the Bondi sphere in shaping the different expanding region observed along the jet. We found that the jet in BL Lac expands with an overall conical geometry. A higher expanding rate region is observed between ~5 and 10 pc (de-projected) from the black hole. Such a region is associated with the decrease in brightness usually observed in high-frequency VLBI images of BL Lac. The jet retrieves the original jet expansion around 17 pc, where the presence of a recollimation shock is supported by both the jet profile and the 15GHz kinematics (MOJAVE survey). The change in the jet expansion profile occurring at ~5 pc could be associated with a change in the external pressure profile in correspondence of the Bondi radius (~3.3X10$^5$$R_s$). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.08952v2-abstract-full').style.display = 'none'; document.getElementById('2102.08952v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 March, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 12 figures. Accepted for publication in Astronomy & Astrophysics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2012.14831">arXiv:2012.14831</a> <span> [<a href="https://arxiv.org/pdf/2012.14831">pdf</a>, <a href="https://arxiv.org/format/2012.14831">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202039612">10.1051/0004-6361/202039612 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Jet collimation in NGC 315 and other nearby AGN </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Boccardi%2C+B">B. Boccardi</a>, <a href="/search/astro-ph?searchtype=author&query=Perucho%2C+M">M. Perucho</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">C. Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Grandi%2C+P">P. Grandi</a>, <a href="/search/astro-ph?searchtype=author&query=Macconi%2C+D">D. Macconi</a>, <a href="/search/astro-ph?searchtype=author&query=Torresi%2C+E">E. Torresi</a>, <a href="/search/astro-ph?searchtype=author&query=Pellegrini%2C+S">S. Pellegrini</a>, <a href="/search/astro-ph?searchtype=author&query=Krichbaum%2C+T+P">T. P. Krichbaum</a>, <a href="/search/astro-ph?searchtype=author&query=Kadler%2C+M">M. Kadler</a>, <a href="/search/astro-ph?searchtype=author&query=Giovannini%2C+G">G. Giovannini</a>, <a href="/search/astro-ph?searchtype=author&query=Karamanavis%2C+V">V. Karamanavis</a>, <a href="/search/astro-ph?searchtype=author&query=Ricci%2C+L">L. Ricci</a>, <a href="/search/astro-ph?searchtype=author&query=Madika%2C+E">E. Madika</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">E. Ros</a>, <a href="/search/astro-ph?searchtype=author&query=Giroletti%2C+M">M. Giroletti</a>, <a href="/search/astro-ph?searchtype=author&query=Zensus%2C+J+A">J. A. Zensus</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2012.14831v1-abstract-short" style="display: inline;"> Aims. The collimation of relativistic jets in galaxies is a poorly understood process. Detailed radio studies of the jet collimation region have been performed so far in few individual objects, providing important constraints for jet formation models. However, the extent of the collimation zone as well as the nature of the external medium possibly confining the jet are still debated. Methods. In t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.14831v1-abstract-full').style.display = 'inline'; document.getElementById('2012.14831v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2012.14831v1-abstract-full" style="display: none;"> Aims. The collimation of relativistic jets in galaxies is a poorly understood process. Detailed radio studies of the jet collimation region have been performed so far in few individual objects, providing important constraints for jet formation models. However, the extent of the collimation zone as well as the nature of the external medium possibly confining the jet are still debated. Methods. In this article we present a multi-frequency and multi-scale analysis of the radio galaxy NGC 315, including the use of mm-VLBI data up to 86 GHz, aimed at revealing the evolution of the jet collimation profile. We then consider results from the literature to compare the jet expansion profile in a sample of 27 low-redshift sources, mainly comprising radio galaxies and BL Lacs, classified based on the accretion properties as low-excitation (LEG) and high-excitation (HEG) galaxies. Results.The jet collimation in NGC 315 is completed on sub-parsec scales. A transition from a parabolic to conical jet shape is detected at $z_{t}=0.58\pm0.28$ parsecs or ${\sim}5\times 10^3$ Schwarzschild radii ($R_{S}$) from the central engine, a distance which is much smaller than the Bondi radius, $r_{B}{\sim}92$ $\rm pc$, estimated based on X-ray data. The jet in this and in few other LEGs in our sample may be initially confined by a thick disk extending out to ${\sim}10^3$-$10^4$ $R_{S}$. A comparison between the mass-scaled jet expansion profiles of all sources indicates that jets in HEGs are surrounded by thicker disk-launched sheaths and collimate on larger scales with respect to jets in LEGs. These results suggest that disk winds play an important role in the jet collimation mechanism, particularly in high-luminosity sources. The impact of winds for the origin of the FRI/FRII dichotomy in radio galaxies is also discussed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.14831v1-abstract-full').style.display = 'none'; document.getElementById('2012.14831v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 December, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">14 pages plus appendix, 6 figures. Accepted for publication in A&A</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2012.10254">arXiv:2012.10254</a> <span> [<a href="https://arxiv.org/pdf/2012.10254">pdf</a>, <a href="https://arxiv.org/format/2012.10254">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202038949">10.1051/0004-6361/202038949 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observation of a sudden cessation of a very-high-energy gamma-ray flare in PKS 1510-089 with H.E.S.S. and MAGIC in May 2016 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Collaboration%2C+H+E+S+S">H. E. S. S. Collaboration</a>, <a href="/search/astro-ph?searchtype=author&query=Abdalla%2C+H">H. Abdalla</a>, <a href="/search/astro-ph?searchtype=author&query=Adam%2C+R">R. Adam</a>, <a href="/search/astro-ph?searchtype=author&query=Aharonian%2C+F">F. Aharonian</a>, <a href="/search/astro-ph?searchtype=author&query=Benkhali%2C+F+A">F. Ait Benkhali</a>, <a href="/search/astro-ph?searchtype=author&query=Ang%C3%BCner%2C+E+O">E. O. Ang眉ner</a>, <a href="/search/astro-ph?searchtype=author&query=Arcaro%2C+C">C. Arcaro</a>, <a href="/search/astro-ph?searchtype=author&query=Arm%2C+C">C. Arm</a>, <a href="/search/astro-ph?searchtype=author&query=Armstrong%2C+T">T. Armstrong</a>, <a href="/search/astro-ph?searchtype=author&query=Ashkar%2C+H">H. Ashkar</a>, <a href="/search/astro-ph?searchtype=author&query=Backes%2C+M">M. Backes</a>, <a href="/search/astro-ph?searchtype=author&query=Baghmanyan%2C+V">V. Baghmanyan</a>, <a href="/search/astro-ph?searchtype=author&query=Martins%2C+V+B">V. Barbosa Martins</a>, <a href="/search/astro-ph?searchtype=author&query=Barnacka%2C+A">A. Barnacka</a>, <a href="/search/astro-ph?searchtype=author&query=Barnard%2C+M">M. Barnard</a>, <a href="/search/astro-ph?searchtype=author&query=Becherini%2C+Y">Y. Becherini</a>, <a href="/search/astro-ph?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/astro-ph?searchtype=author&query=Bernl%C3%B6hr%2C+K">K. Bernl枚hr</a>, <a href="/search/astro-ph?searchtype=author&query=Bi%2C+B">B. Bi</a>, <a href="/search/astro-ph?searchtype=author&query=B%C3%B6ttcher%2C+M">M. B枚ttcher</a>, <a href="/search/astro-ph?searchtype=author&query=Boisson%2C+C">C. Boisson</a>, <a href="/search/astro-ph?searchtype=author&query=Bolmont%2C+J">J. Bolmont</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnefoy%2C+S">S. Bonnefoy</a>, <a href="/search/astro-ph?searchtype=author&query=de+Lavergne%2C+M+d+B">M. de Bony de Lavergne</a>, <a href="/search/astro-ph?searchtype=author&query=Bregeon%2C+J">J. Bregeon</a> , et al. (409 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2012.10254v1-abstract-short" style="display: inline;"> The flat spectrum radio quasar (FSRQ) PKS 1510-089 is known for its complex multiwavelength behavior, and is one of only a few FSRQs detected at very high energy (VHE, $E>100\,$GeV) $纬$-rays. VHE $纬$-ray observations with H.E.S.S. and MAGIC during late May and early June 2016 resulted in the detection of an unprecedented flare, which reveals for the first time VHE $纬$-ray intranight variability in… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.10254v1-abstract-full').style.display = 'inline'; document.getElementById('2012.10254v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2012.10254v1-abstract-full" style="display: none;"> The flat spectrum radio quasar (FSRQ) PKS 1510-089 is known for its complex multiwavelength behavior, and is one of only a few FSRQs detected at very high energy (VHE, $E>100\,$GeV) $纬$-rays. VHE $纬$-ray observations with H.E.S.S. and MAGIC during late May and early June 2016 resulted in the detection of an unprecedented flare, which reveals for the first time VHE $纬$-ray intranight variability in this source. While a common variability timescale of $1.5\,$hr is found, there is a significant deviation near the end of the flare with a timescale of $\sim 20\,$min marking the cessation of the event. The peak flux is nearly two orders of magnitude above the low-level emission. For the first time, curvature is detected in the VHE $纬$-ray spectrum of PKS 1510-089, which is fully explained through absorption by the extragalactic background light. Optical R-band observations with ATOM reveal a counterpart of the $纬$-ray flare, even though the detailed flux evolution differs from the VHE ightcurve. Interestingly, a steep flux decrease is observed at the same time as the cessation of the VHE flare. In the high energy (HE, $E>100\,$MeV) $纬$-ray band only a moderate flux increase is observed with Fermi-LAT, while the HE $纬$-ray spectrum significantly hardens up to a photon index of 1.6. A search for broad-line region (BLR) absorption features in the $纬$-ray spectrum indicates that the emission region is located outside of the BLR. Radio VLBI observations reveal a fast moving knot interacting with a standing jet feature around the time of the flare. As the standing feature is located $\sim 50\,$pc from the black hole, the emission region of the flare may have been located at a significant distance from the black hole. If this correlation is indeed true, VHE $纬$ rays have been produced far down the jet where turbulent plasma crosses a standing shock. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.10254v1-abstract-full').style.display = 'none'; document.getElementById('2012.10254v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 December, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">25 pages, 17 figures. Accepted for publication by Astronomy & Astrophysics. Corresponding authors: M. Zacharias, J. Sitarek, D. Sanchez, T. Terzic</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 648, A23 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2012.00008">arXiv:2012.00008</a> <span> [<a href="https://arxiv.org/pdf/2012.00008">pdf</a>, <a href="https://arxiv.org/format/2012.00008">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/staa3777">10.1093/mnras/staa3777 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> RoboPol: AGN polarimetric monitoring data </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D">D. Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Kiehlmann%2C+S">S. Kiehlmann</a>, <a href="/search/astro-ph?searchtype=author&query=Pavlidou%2C+V">V. Pavlidou</a>, <a href="/search/astro-ph?searchtype=author&query=Panopoulou%2C+G+V">G. V. Panopoulou</a>, <a href="/search/astro-ph?searchtype=author&query=Skalidis%2C+R">R. Skalidis</a>, <a href="/search/astro-ph?searchtype=author&query=Angelakis%2C+E">E. Angelakis</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">C. Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Einoder%2C+E+N">E. N. Einoder</a>, <a href="/search/astro-ph?searchtype=author&query=Hovatta%2C+T">T. Hovatta</a>, <a href="/search/astro-ph?searchtype=author&query=Kokolakis%2C+K">K. Kokolakis</a>, <a href="/search/astro-ph?searchtype=author&query=Kougentakis%2C+A">A. Kougentakis</a>, <a href="/search/astro-ph?searchtype=author&query=Kus%2C+A">A. Kus</a>, <a href="/search/astro-ph?searchtype=author&query=Kylafis%2C+N">N. Kylafis</a>, <a href="/search/astro-ph?searchtype=author&query=Kyritsis%2C+E">E. Kyritsis</a>, <a href="/search/astro-ph?searchtype=author&query=Lalakos%2C+A">A. Lalakos</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">I. Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Maharana%2C+S">S. Maharana</a>, <a href="/search/astro-ph?searchtype=author&query=Makrydopoulou%2C+E">E. Makrydopoulou</a>, <a href="/search/astro-ph?searchtype=author&query=Mandarakas%2C+N">N. Mandarakas</a>, <a href="/search/astro-ph?searchtype=author&query=Maragkakis%2C+G+M">G. M. Maragkakis</a>, <a href="/search/astro-ph?searchtype=author&query=Myserlis%2C+I">I. Myserlis</a>, <a href="/search/astro-ph?searchtype=author&query=Papadakis%2C+I">I. Papadakis</a>, <a href="/search/astro-ph?searchtype=author&query=Paterakis%2C+G">G. Paterakis</a>, <a href="/search/astro-ph?searchtype=author&query=Pearson%2C+T+J">T. J. Pearson</a>, <a href="/search/astro-ph?searchtype=author&query=Ramaprakash%2C+A+N">A. N. Ramaprakash</a> , et al. (7 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2012.00008v1-abstract-short" style="display: inline;"> We present uniformly reprocessed and re-calibrated data from the RoboPol programme of optopolarimetric monitoring of active galactic nuclei (AGN), covering observations between 2013, when the instrument was commissioned, and 2017. In total, the dataset presented in this paper includes 5068 observations of 222 AGN with Dec > -25 deg. We describe the current version of the RoboPol pipeline that was… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.00008v1-abstract-full').style.display = 'inline'; document.getElementById('2012.00008v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2012.00008v1-abstract-full" style="display: none;"> We present uniformly reprocessed and re-calibrated data from the RoboPol programme of optopolarimetric monitoring of active galactic nuclei (AGN), covering observations between 2013, when the instrument was commissioned, and 2017. In total, the dataset presented in this paper includes 5068 observations of 222 AGN with Dec > -25 deg. We describe the current version of the RoboPol pipeline that was used to process and calibrate the entire dataset, and we make the data publicly available for use by the astronomical community. Average quantities summarising optopolarimetric behaviour (average degree of polarization, polarization variability index) are also provided for each source we have observed and for the time interval we have followed it. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.00008v1-abstract-full').style.display = 'none'; document.getElementById('2012.00008v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 November, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted to MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2002.00982">arXiv:2002.00982</a> <span> [<a href="https://arxiv.org/pdf/2002.00982">pdf</a>, <a href="https://arxiv.org/format/2002.00982">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Cosmology and Nongalactic Astrophysics">astro-ph.CO</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202037444">10.1051/0004-6361/202037444 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Global alignments of parsec-scale AGN radio jets and their polarization planes </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D">D. Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">C. Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Mandarakas%2C+N">N. Mandarakas</a>, <a href="/search/astro-ph?searchtype=author&query=Angelakis%2C+E">E. Angelakis</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2002.00982v2-abstract-short" style="display: inline;"> A number of works reported on the existence of a large scale alignment of the polarization plane of extragalactic sources as well as the alignment of radio-sources structural axes. However, both claims and their interpretation remain controversial. For the first time we explore the parsec-scale jets alignments. Additionally, we use archival polarimetric data at different wavelengths in order to co… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2002.00982v2-abstract-full').style.display = 'inline'; document.getElementById('2002.00982v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2002.00982v2-abstract-full" style="display: none;"> A number of works reported on the existence of a large scale alignment of the polarization plane of extragalactic sources as well as the alignment of radio-sources structural axes. However, both claims and their interpretation remain controversial. For the first time we explore the parsec-scale jets alignments. Additionally, we use archival polarimetric data at different wavelengths in order to compare relative orientations of the jets and the polarization planes of their emission. Using the flux density distribution in very long baseline interferometry (VLBI) radio maps from the Astrogeo database, we determine the parsec-scale jet orientation for the largest sample of active galactic nuclei (AGN) to date. Employing the method of parallel transport and a sample statistics characterizing the jet orientation dispersion among neighbors, we test whether the identified jets are significantly aligned. We show that the parsec-scale jets in our sample do not demonstrate any significant global alignments. Moreover, the jet direction is found to be weakly correlated with the polarization plane direction at different frequencies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2002.00982v2-abstract-full').style.display = 'none'; document.getElementById('2002.00982v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 February, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 February, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">8 pages, 9 figures, accepted by Astronomy and Astrophysics</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 635, A102 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2001.06512">arXiv:2001.06512</a> <span> [<a href="https://arxiv.org/pdf/2001.06512">pdf</a>, <a href="https://arxiv.org/format/2001.06512">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/staa082">10.1093/mnras/staa082 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Multiwavelength behaviour of the blazar 3C279: decade-long study from $纬$-ray to radio </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Larionov%2C+V+M">V. M. Larionov</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">S. G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">A. P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Villata%2C+M">M. Villata</a>, <a href="/search/astro-ph?searchtype=author&query=Raiteri%2C+C+M">C. M. Raiteri</a>, <a href="/search/astro-ph?searchtype=author&query=Smith%2C+P+S">P. S. Smith</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">I. Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Savchenko%2C+S+S">S. S. Savchenko</a>, <a href="/search/astro-ph?searchtype=author&query=Morozova%2C+D+A">D. A. Morozova</a>, <a href="/search/astro-ph?searchtype=author&query=Acosta-Pulido%2C+J+A">J. A. Acosta-Pulido</a>, <a href="/search/astro-ph?searchtype=author&query=Aller%2C+M+F">M. F. Aller</a>, <a href="/search/astro-ph?searchtype=author&query=Aller%2C+H+D">H. D. Aller</a>, <a href="/search/astro-ph?searchtype=author&query=Andreeva%2C+T+S">T. S. Andreeva</a>, <a href="/search/astro-ph?searchtype=author&query=Arkharov%2C+A+A">A. A. Arkharov</a>, <a href="/search/astro-ph?searchtype=author&query=Bachev%2C+R">R. Bachev</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">G. Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Borman%2C+G+A">G. A. Borman</a>, <a href="/search/astro-ph?searchtype=author&query=Bozhilov%2C+V">V. Bozhilov</a>, <a href="/search/astro-ph?searchtype=author&query=Calcidese%2C+P">P. Calcidese</a>, <a href="/search/astro-ph?searchtype=author&query=Carnerero%2C+M+I">M. I. Carnerero</a>, <a href="/search/astro-ph?searchtype=author&query=Carosati%2C+D">D. Carosati</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">C. Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+W+-">W. -P. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Damljanovic%2C+G">G. Damljanovic</a>, <a href="/search/astro-ph?searchtype=author&query=Dementyev%2C+A+V">A. V. Dementyev</a> , et al. (62 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2001.06512v1-abstract-short" style="display: inline;"> We report the results of decade-long (2008-2018) $纬$-ray to 1 GHz radio monitoring of the blazar 3C 279, including GASP/WEBT, $\it{Fermi}$ and $\it{Swift}$ data, as well as polarimetric and spectroscopic data. The X-ray and $纬$-ray light curves correlate well, with no delay > 3 hours, implying general co-spatiality of the emission regions. The $纬$-ray-optical flux-flux relation changes with activi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2001.06512v1-abstract-full').style.display = 'inline'; document.getElementById('2001.06512v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2001.06512v1-abstract-full" style="display: none;"> We report the results of decade-long (2008-2018) $纬$-ray to 1 GHz radio monitoring of the blazar 3C 279, including GASP/WEBT, $\it{Fermi}$ and $\it{Swift}$ data, as well as polarimetric and spectroscopic data. The X-ray and $纬$-ray light curves correlate well, with no delay > 3 hours, implying general co-spatiality of the emission regions. The $纬$-ray-optical flux-flux relation changes with activity state, ranging from a linear to a more complex dependence. The behaviour of the Stokes parameters at optical and radio wavelengths, including 43 GHz VLBA images, supports either a predominantly helical magnetic field or motion of the radiating plasma along a spiral path. Apparent speeds of emission knots range from 10 to 37c, with the highest values requiring bulk Lorentz factors close to those needed to explain $纬$-ray variability on very short time scales. The Mg II emission line flux in the `blue' and `red' wings correlates with the optical synchrotron continuum flux density, possibly providing a variable source of seed photons for inverse Compton scattering. In the radio bands we find progressive delays of the most prominent light curve maxima with decreasing frequency, as expected from the frequency dependence of the $蟿=1$ surface of synchrotron self-absorption. The global maximum in the 86 GHz light curve becomes less prominent at lower frequencies, while a local maximum, appearing in 2014, strengthens toward decreasing frequencies, becoming pronounced at $\sim5$ GHz. These tendencies suggest different Doppler boosting of stratified radio-emitting zones in the jet. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2001.06512v1-abstract-full').style.display = 'none'; document.getElementById('2001.06512v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 January, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages, 18 figures, accepted for publication in MNRAS</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> MNRAS 492 (2020) 3829 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1910.03609">arXiv:1910.03609</a> <span> [<a href="https://arxiv.org/pdf/1910.03609">pdf</a>, <a href="https://arxiv.org/ps/1910.03609">ps</a>, <a href="https://arxiv.org/format/1910.03609">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stz2792">10.1093/mnras/stz2792 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Investigating the multiwavelength behaviour of the flat spectrum radio quasar CTA 102 during 2013-2017 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=D%27Ammando%2C+F">F. D'Ammando</a>, <a href="/search/astro-ph?searchtype=author&query=Raiteri%2C+C+M">C. M. Raiteri</a>, <a href="/search/astro-ph?searchtype=author&query=Villata%2C+M">M. Villata</a>, <a href="/search/astro-ph?searchtype=author&query=Acosta-Pulido%2C+J+A">J. A. Acosta-Pulido</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">I. Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Arkharov%2C+A+A">A. A. Arkharov</a>, <a href="/search/astro-ph?searchtype=author&query=Bachev%2C+R">R. Bachev</a>, <a href="/search/astro-ph?searchtype=author&query=Baida%2C+G+V">G. V. Baida</a>, <a href="/search/astro-ph?searchtype=author&query=Benitez%2C+E">E. Benitez</a>, <a href="/search/astro-ph?searchtype=author&query=Borman%2C+G+A">G. A. Borman</a>, <a href="/search/astro-ph?searchtype=author&query=Boschin%2C+W">W. Boschin</a>, <a href="/search/astro-ph?searchtype=author&query=Bozhilov%2C+V">V. Bozhilov</a>, <a href="/search/astro-ph?searchtype=author&query=Butuzova%2C+M+S">M. S. Butuzova</a>, <a href="/search/astro-ph?searchtype=author&query=Calcidese%2C+P">P. Calcidese</a>, <a href="/search/astro-ph?searchtype=author&query=Carnerero%2C+M+I">M. I. Carnerero</a>, <a href="/search/astro-ph?searchtype=author&query=Carosati%2C+D">D. Carosati</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">C. Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Castro-Segura%2C+N">N. Castro-Segura</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+W+-">W. -P. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Damljanovic%2C+G">G. Damljanovic</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Paola%2C+A">A. Di Paola</a>, <a href="/search/astro-ph?searchtype=author&query=Echevarria%2C+J">J. Echevarria</a>, <a href="/search/astro-ph?searchtype=author&query=Efimova%2C+N+V">N. V. Efimova</a>, <a href="/search/astro-ph?searchtype=author&query=Ehgamberdiev%2C+S+A">Sh. A. Ehgamberdiev</a>, <a href="/search/astro-ph?searchtype=author&query=Espinosa%2C+C">C. Espinosa</a> , et al. (72 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1910.03609v2-abstract-short" style="display: inline;"> We present a multiwavelength study of the flat-spectrum radio quasar CTA 102 during 2013-2017. We use radio-to-optical data obtained by the Whole Earth Blazar Telescope, 15 GHz data from the Owens Valley Radio Observatory, 91 and 103 GHz data from the Atacama Large Millimeter Array, near-infrared data from the Rapid Eye Monitor telescope, as well as data from the Swift (optical-UV and X-rays) and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.03609v2-abstract-full').style.display = 'inline'; document.getElementById('1910.03609v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1910.03609v2-abstract-full" style="display: none;"> We present a multiwavelength study of the flat-spectrum radio quasar CTA 102 during 2013-2017. We use radio-to-optical data obtained by the Whole Earth Blazar Telescope, 15 GHz data from the Owens Valley Radio Observatory, 91 and 103 GHz data from the Atacama Large Millimeter Array, near-infrared data from the Rapid Eye Monitor telescope, as well as data from the Swift (optical-UV and X-rays) and Fermi ($纬$ rays) satellites to study flux and spectral variability and the correlation between flux changes at different wavelengths. Unprecedented $纬$-ray flaring activity was observed during 2016 November-2017 February, with four major outbursts. A peak flux of (2158 $\pm$ 63)$\times$10$^{-8}$ ph cm$^{-2}$ s$^{-1}$, corresponding to a luminosity of (2.2 $\pm$ 0.1)$\times$10$^{50}$ erg s$^{-1}$, was reached on 2016 December 28. These four $纬$-ray outbursts have corresponding events in the near-infrared, optical, and UV bands, with the peaks observed at the same time. A general agreement between X-ray and $纬$-ray activity is found. The $纬$-ray flux variations show a general, strong correlation with the optical ones with no time lag between the two bands and a comparable variability amplitude. This $纬$-ray/optical relationship is in agreement with the geometrical model that has successfully explained the low-energy flux and spectral behaviour, suggesting that the long-term flux variations are mainly due to changes in the Doppler factor produced by variations of the viewing angle of the emitting regions. The difference in behaviour between radio and higher energy emission would be ascribed to different viewing angles of the jet regions producing their emission. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.03609v2-abstract-full').style.display = 'none'; document.getElementById('1910.03609v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 November, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 October, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">24 pages, 18 figures, and 4 tables. Accepted for publication in Monthly Notices of the Royal Astronomical Society</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1902.08367">arXiv:1902.08367</a> <span> [<a href="https://arxiv.org/pdf/1902.08367">pdf</a>, <a href="https://arxiv.org/ps/1902.08367">ps</a>, <a href="https://arxiv.org/format/1902.08367">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stz557">10.1093/mnras/stz557 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> RoboPol: A four-channel optical imaging polarimeter </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ramaprakash%2C+A+N">A. N. Ramaprakash</a>, <a href="/search/astro-ph?searchtype=author&query=Rajarshi%2C+C+V">C. V. Rajarshi</a>, <a href="/search/astro-ph?searchtype=author&query=Das%2C+H+K">H. K. Das</a>, <a href="/search/astro-ph?searchtype=author&query=Khodade%2C+P">P. Khodade</a>, <a href="/search/astro-ph?searchtype=author&query=Modi%2C+D">D. Modi</a>, <a href="/search/astro-ph?searchtype=author&query=Panopoulou%2C+G">G. Panopoulou</a>, <a href="/search/astro-ph?searchtype=author&query=Maharana%2C+S">S. Maharana</a>, <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D">D. Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Angelakis%2C+E">E. Angelakis</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">C. Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Fuhrmann%2C+L">L. Fuhrmann</a>, <a href="/search/astro-ph?searchtype=author&query=Hovatta%2C+T">T. Hovatta</a>, <a href="/search/astro-ph?searchtype=author&query=Kiehlmann%2C+S">S. Kiehlmann</a>, <a href="/search/astro-ph?searchtype=author&query=King%2C+O+G">O. G. King</a>, <a href="/search/astro-ph?searchtype=author&query=Kylafis%2C+N">N. Kylafis</a>, <a href="/search/astro-ph?searchtype=author&query=Kougentakis%2C+A">A. Kougentakis</a>, <a href="/search/astro-ph?searchtype=author&query=Kus%2C+A">A. Kus</a>, <a href="/search/astro-ph?searchtype=author&query=Mahabal%2C+A">A. Mahabal</a>, <a href="/search/astro-ph?searchtype=author&query=Marecki%2C+A">A. Marecki</a>, <a href="/search/astro-ph?searchtype=author&query=Myserlis%2C+I">I. Myserlis</a>, <a href="/search/astro-ph?searchtype=author&query=Paterakis%2C+G">G. Paterakis</a>, <a href="/search/astro-ph?searchtype=author&query=Paleologou%2C+E">E. Paleologou</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">I. Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Papadakis%2C+I">I. Papadakis</a>, <a href="/search/astro-ph?searchtype=author&query=Papamastorakis%2C+I">I. Papamastorakis</a> , et al. (8 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1902.08367v1-abstract-short" style="display: inline;"> We present the design and performance of RoboPol, a four-channel optical polarimeter operating at the Skinakas Observatory in Crete, Greece. RoboPol is capable of measuring both relative linear Stokes parameters $q$ and $u$ (and the total intensity $I$) in one sky exposure. Though primarily used to measure the polarization of point sources in the R-band, the instrument features additional filters… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.08367v1-abstract-full').style.display = 'inline'; document.getElementById('1902.08367v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1902.08367v1-abstract-full" style="display: none;"> We present the design and performance of RoboPol, a four-channel optical polarimeter operating at the Skinakas Observatory in Crete, Greece. RoboPol is capable of measuring both relative linear Stokes parameters $q$ and $u$ (and the total intensity $I$) in one sky exposure. Though primarily used to measure the polarization of point sources in the R-band, the instrument features additional filters (B, V and I), enabling multi-wavelength imaging polarimetry over a large field of view (13.6' $\times$ 13.6'). We demonstrate the accuracy and stability of the instrument throughout its five years of operation. Best performance is achieved within the central region of the field of view and in the R band. For such measurements the systematic uncertainty is below 0.1% in fractional linear polarization, $p$ (0.05% maximum likelihood). Throughout all observing seasons the instrumental polarization varies within 0.1% in $p$ and within 1$^\circ$ in polarization angle. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.08367v1-abstract-full').style.display = 'none'; document.getElementById('1902.08367v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 February, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 15 figures, accepted for publication in MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1812.02194">arXiv:1812.02194</a> <span> [<a href="https://arxiv.org/pdf/1812.02194">pdf</a>, <a href="https://arxiv.org/format/1812.02194">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201834519">10.1051/0004-6361/201834519 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The magnetic field structure in CTA 102 from high resolution mm-VLBI observations during the flaring state in 2016-2017 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">Carolina Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D+A">Dmitry A. Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=MacDonald%2C+N+R">Nicholas R. MacDonald</a>, <a href="/search/astro-ph?searchtype=author&query=Krichbaum%2C+T+P">Thomas P. Krichbaum</a>, <a href="/search/astro-ph?searchtype=author&query=Boccardi%2C+B">Biagina Boccardi</a>, <a href="/search/astro-ph?searchtype=author&query=Traianou%2C+E">Efthalia Traianou</a>, <a href="/search/astro-ph?searchtype=author&query=G%C3%B3mez%2C+J+L">Jos茅 L. G贸mez</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Sohn%2C+B">Bong-Won Sohn</a>, <a href="/search/astro-ph?searchtype=author&query=Bremer%2C+M">Michael Bremer</a>, <a href="/search/astro-ph?searchtype=author&query=Hodgson%2C+J">Jeffrey Hodgson</a>, <a href="/search/astro-ph?searchtype=author&query=Kallunki%2C+J">Juha Kallunki</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+J">Jae-Young Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Williamson%2C+K+E">Karen E. Williamson</a>, <a href="/search/astro-ph?searchtype=author&query=Zensus%2C+J+A">J. Anton Zensus</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1812.02194v2-abstract-short" style="display: inline;"> Investigating the magnetic field structure in the innermost regions of relativistic jets is fundamental to shed light on the crucial physical processes giving rise to the jet formation, as well as to its extraordinary radiation output up to gamma-ray energies. We study the magnetic field structure of the quasar CTA 102 with 3 and 7 mm-VLBI polarimetric observations, reaching an unprecedented resol… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1812.02194v2-abstract-full').style.display = 'inline'; document.getElementById('1812.02194v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1812.02194v2-abstract-full" style="display: none;"> Investigating the magnetic field structure in the innermost regions of relativistic jets is fundamental to shed light on the crucial physical processes giving rise to the jet formation, as well as to its extraordinary radiation output up to gamma-ray energies. We study the magnetic field structure of the quasar CTA 102 with 3 and 7 mm-VLBI polarimetric observations, reaching an unprecedented resolution (~50 microarcsec). We also investigate the variability and physical process occurring in the source during the observing period which coincides with a very active state of the source till high-energies. The Faraday rotation analysis between 3 and 7mm shows a gradient in rotation measure with a maximum value of ~6X10^4 rad/m^2 and intrinsic electric vector position angles (EVPAs) oriented around the centroid of the core, suggesting the presence of large-scale helical magnetic fields. Such a magnetic field structure is also visible in 7 mm images when a new superluminal component is crossing the core region. The 7mm EVPAs orientation is different when the component is exiting the core or crossing a stationary feature at ~0.1 mas. The interaction between the superluminal component and a recollimation shock at ~0.1 mas could have triggered the multi-wavelengths flares. The variability Doppler factor associated with such interaction is large enough to explain the high energy emission, as we infer from the analysis of gamma-ray and X-ray data, and it is in agreement with the Doppler factor obtained to explain the extraordinary optical flare by Raiteri et al.(2017). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1812.02194v2-abstract-full').style.display = 'none'; document.getElementById('1812.02194v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 February, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 December, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Published in Astronomy & Astrophysics</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 622, A158 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1811.07654">arXiv:1811.07654</a> <span> [<a href="https://arxiv.org/pdf/1811.07654">pdf</a>, <a href="https://arxiv.org/ps/1811.07654">ps</a>, <a href="https://arxiv.org/format/1811.07654">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201732532">10.1051/0004-6361/201732532 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> AGILE, Fermi, Swift, and GASP-WEBT multi-wavelength observations of the high-redshift blazar 4C $+$71.07 in outburst </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Vercellone%2C+S">S. Vercellone</a>, <a href="/search/astro-ph?searchtype=author&query=Romano%2C+P">P. Romano</a>, <a href="/search/astro-ph?searchtype=author&query=Piano%2C+G">G. Piano</a>, <a href="/search/astro-ph?searchtype=author&query=Vittorini%2C+V">V. Vittorini</a>, <a href="/search/astro-ph?searchtype=author&query=Donnarumma%2C+I">I. Donnarumma</a>, <a href="/search/astro-ph?searchtype=author&query=Munar-Adrover%2C+P">P. Munar-Adrover</a>, <a href="/search/astro-ph?searchtype=author&query=Raiteri%2C+C+M">C. M. Raiteri</a>, <a href="/search/astro-ph?searchtype=author&query=Villata%2C+M">M. Villata</a>, <a href="/search/astro-ph?searchtype=author&query=Verrecchia%2C+F">F. Verrecchia</a>, <a href="/search/astro-ph?searchtype=author&query=Lucarelli%2C+F">F. Lucarelli</a>, <a href="/search/astro-ph?searchtype=author&query=Pittori%2C+C">C. Pittori</a>, <a href="/search/astro-ph?searchtype=author&query=Bulgarelli%2C+A">A. Bulgarelli</a>, <a href="/search/astro-ph?searchtype=author&query=Fioretti%2C+V">V. Fioretti</a>, <a href="/search/astro-ph?searchtype=author&query=Tavani%2C+M">M. Tavani</a>, <a href="/search/astro-ph?searchtype=author&query=Acosta-Pulido%2C+J+A">J. A. Acosta-Pulido</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">I. Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Arkharov%2C+A+A">A. A. Arkharov</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Bachev%2C+R">R. Bachev</a>, <a href="/search/astro-ph?searchtype=author&query=Borman%2C+G+A">G. A. Borman</a>, <a href="/search/astro-ph?searchtype=author&query=Butuzova%2C+M+S">M. S. Butuzova</a>, <a href="/search/astro-ph?searchtype=author&query=Carnerero%2C+M+I">M. I. Carnerero</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">C. Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Damljanovic%2C+G">G. Damljanovic</a>, <a href="/search/astro-ph?searchtype=author&query=D%27Ammando%2C+F">F. D'Ammando</a> , et al. (34 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1811.07654v1-abstract-short" style="display: inline;"> The flat-spectrum radio quasar 4C $+$71.07 is a high-redshift ($z=2.172$), $纬$-loud blazar whose optical emission is dominated by the thermal radiation from accretion disc. 4C $+$71.07 has been detected in outburst twice by the AGILE $纬$-ray satellite during the period end of October - mid November 2015, when it reached a $纬$-ray flux of the order of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1811.07654v1-abstract-full').style.display = 'inline'; document.getElementById('1811.07654v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1811.07654v1-abstract-full" style="display: none;"> The flat-spectrum radio quasar 4C $+$71.07 is a high-redshift ($z=2.172$), $纬$-loud blazar whose optical emission is dominated by the thermal radiation from accretion disc. 4C $+$71.07 has been detected in outburst twice by the AGILE $纬$-ray satellite during the period end of October - mid November 2015, when it reached a $纬$-ray flux of the order of $F_{\rm E>100\,MeV} = (1.2 \pm 0.3)\times 10^{-6}$ photons cm$^{-2}$ s$^{-1}$ and $F_{\rm E>100\,MeV} = (3.1 \pm 0.6)\times 10^{-6}$ photons cm$^{-2}$ s$^{-1}$, respectively, allowing us to investigate the properties of the jet and of the emission region. We investigated its spectral energy distribution by means of almost simultaneous observations covering the cm, mm, near-infrared, optical, ultra-violet, X-ray and $纬$-ray energy bands obtained by the GASP-WEBT Consortium, the Swift and the AGILE and Fermi satellites. The spectral energy distribution of the second $纬$-ray flare (the one whose energy coverage is more dense) can be modelled by means of a one-zone leptonic model, yielding a total jet power of about $4\times10^{47}$ erg s$^{-1}$. During the most prominent $纬$-ray flaring period our model is consistent with a dissipation region within the broad-line region. Moreover, this class of high-redshift, large-mass black-hole flat-spectrum radio quasars might be good targets for future $纬$-ray satellites such as e-ASTROGAM. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1811.07654v1-abstract-full').style.display = 'none'; document.getElementById('1811.07654v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 November, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in A&A. 9 pages, 4 Figures, 3 Tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 621, A82 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1808.00469">arXiv:1808.00469</a> <span> [<a href="https://arxiv.org/pdf/1808.00469">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1126/science.aau8815">10.1126/science.aau8815 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Compact radio emission indicates a structured jet was produced by a binary neutron star merger </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ghirlanda%2C+G">G. Ghirlanda</a>, <a href="/search/astro-ph?searchtype=author&query=Salafia%2C+O+S">O. S. Salafia</a>, <a href="/search/astro-ph?searchtype=author&query=Paragi%2C+Z">Z. Paragi</a>, <a href="/search/astro-ph?searchtype=author&query=Giroletti%2C+M">M. Giroletti</a>, <a href="/search/astro-ph?searchtype=author&query=Yang%2C+J">J. Yang</a>, <a href="/search/astro-ph?searchtype=author&query=Marcote%2C+B">B. Marcote</a>, <a href="/search/astro-ph?searchtype=author&query=Blanchard%2C+J">J. Blanchard</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">I. Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=An%2C+T">T. An</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardini%2C+M+G">M. G. Bernardini</a>, <a href="/search/astro-ph?searchtype=author&query=Beswick%2C+R">R. Beswick</a>, <a href="/search/astro-ph?searchtype=author&query=Branchesi%2C+M">M. Branchesi</a>, <a href="/search/astro-ph?searchtype=author&query=Campana%2C+S">S. Campana</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">C. Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Chassande-Mottin%2C+E">E. Chassande-Mottin</a>, <a href="/search/astro-ph?searchtype=author&query=Colpi%2C+M">M. Colpi</a>, <a href="/search/astro-ph?searchtype=author&query=Covino%2C+S">S. Covino</a>, <a href="/search/astro-ph?searchtype=author&query=D%27Avanzo%2C+P">P. D'Avanzo</a>, <a href="/search/astro-ph?searchtype=author&query=D%27Elia%2C+V">V. D'Elia</a>, <a href="/search/astro-ph?searchtype=author&query=Frey%2C+S">S. Frey</a>, <a href="/search/astro-ph?searchtype=author&query=Gawronski%2C+M">M. Gawronski</a>, <a href="/search/astro-ph?searchtype=author&query=Ghisellini%2C+G">G. Ghisellini</a>, <a href="/search/astro-ph?searchtype=author&query=Gurvits%2C+L+I">L. I. Gurvits</a>, <a href="/search/astro-ph?searchtype=author&query=Jonker%2C+P+G">P. G. Jonker</a>, <a href="/search/astro-ph?searchtype=author&query=van+Langevelde%2C+H+J">H. J. van Langevelde</a> , et al. (11 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1808.00469v2-abstract-short" style="display: inline;"> The binary neutron star merger event GW170817 was detected through both electromagnetic radiation and gravitational waves. Its afterglow emission may have been produced by either a narrow relativistic jet or an isotropic outflow. High spatial resolution measurements of the source size and displacement can discriminate between these scenarios. We present Very Long Baseline Interferometry observatio… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1808.00469v2-abstract-full').style.display = 'inline'; document.getElementById('1808.00469v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1808.00469v2-abstract-full" style="display: none;"> The binary neutron star merger event GW170817 was detected through both electromagnetic radiation and gravitational waves. Its afterglow emission may have been produced by either a narrow relativistic jet or an isotropic outflow. High spatial resolution measurements of the source size and displacement can discriminate between these scenarios. We present Very Long Baseline Interferometry observations, performed 207.4 days after the merger, using a global network of 32 radio telescopes. The apparent source size is constrained to be smaller than 2.5 milliarcseconds at the 90% confidence level. This excludes the isotropic outflow scenario, which would have produced a larger apparent size, indicating that GW170817 produced a structured relativistic jet. Our rate calculations show that at least 10% of neutron star mergers produce such a jet. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1808.00469v2-abstract-full').style.display = 'none'; document.getElementById('1808.00469v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 February, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 1 August, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">28 pages, 10 figures, 2 tables. This is the author's version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. The definitive version was published in Science , (2019-02-21), doi: 10.1126/science.aau8815</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1807.11145">arXiv:1807.11145</a> <span> [<a href="https://arxiv.org/pdf/1807.11145">pdf</a>, <a href="https://arxiv.org/ps/1807.11145">ps</a>, <a href="https://arxiv.org/format/1807.11145">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/aad553">10.3847/1538-4357/aad553 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Optical Emission and Particle Acceleration in a Quasi-Stationary Component in the Jet of OJ~287 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Sasada%2C+M">Mahito Sasada</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S">Svetlana Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Bala%2C+V">Vishal Bala</a>, <a href="/search/astro-ph?searchtype=author&query=Joshi%2C+M">Manasvita Joshi</a>, <a href="/search/astro-ph?searchtype=author&query=MacDonald%2C+N+R">Nicholas R. MacDonald</a>, <a href="/search/astro-ph?searchtype=author&query=Malmrose%2C+M+P">Michael P. Malmrose</a>, <a href="/search/astro-ph?searchtype=author&query=Larionov%2C+V+M">Valeri M. Larionov</a>, <a href="/search/astro-ph?searchtype=author&query=Morozova%2C+D+A">Daria A. Morozova</a>, <a href="/search/astro-ph?searchtype=author&query=Troitsky%2C+I+S">Ivan S. Troitsky</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">Carolina Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=G%C3%B3mez%2C+J+L">Jos茅 L. G贸mez</a>, <a href="/search/astro-ph?searchtype=author&query=Molina%2C+S+N">Sol N. Molina</a>, <a href="/search/astro-ph?searchtype=author&query=Itoh%2C+R">Ryosuke Itoh</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1807.11145v1-abstract-short" style="display: inline;"> We analyze the linear polarization of the relativistic jet in BL Lacertae object OJ~287 as revealed by multi-epoch Very Long Baseline Array (VLBA) images at 43 GHz and monitoring observations at optical bands. The electric-vector position angle (EVPA) of the optical polarization matches that at 43 GHz at locations that are often in the compact millimeter-wave "core" or, at other epochs, coincident… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1807.11145v1-abstract-full').style.display = 'inline'; document.getElementById('1807.11145v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1807.11145v1-abstract-full" style="display: none;"> We analyze the linear polarization of the relativistic jet in BL Lacertae object OJ~287 as revealed by multi-epoch Very Long Baseline Array (VLBA) images at 43 GHz and monitoring observations at optical bands. The electric-vector position angle (EVPA) of the optical polarization matches that at 43 GHz at locations that are often in the compact millimeter-wave "core" or, at other epochs, coincident with a bright, quasi-stationary emission feature $\sim0.2$~milliarcsec ($\sim$0.9~pc projected on the sky) downstream from the core. This implies that electrons with high enough energies to emit optical synchrotron and $纬$-ray inverse Compton radiation are accelerated both in the core and at the downstream feature, the latter of which lies $\geq10$~pc from the central engine. The polarization vector in the stationary feature is nearly parallel to the jet axis, as expected for a conical standing shock capable of accelerating electrons to GeV energies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1807.11145v1-abstract-full').style.display = 'none'; document.getElementById('1807.11145v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 July, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 9 figures, accepted for publication in ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1807.00413">arXiv:1807.00413</a> <span> [<a href="https://arxiv.org/pdf/1807.00413">pdf</a>, <a href="https://arxiv.org/format/1807.00413">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201832677">10.1051/0004-6361/201832677 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Multi-wavelength characterization of the blazar S5~0716+714 during an unprecedented outburst phase </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=MAGIC+Collaboration"> MAGIC Collaboration</a>, <a href="/search/astro-ph?searchtype=author&query=Ahnen%2C+M+L">M. L. Ahnen</a>, <a href="/search/astro-ph?searchtype=author&query=Ansoldi%2C+S">S. Ansoldi</a>, <a href="/search/astro-ph?searchtype=author&query=Antonelli%2C+L+A">L. A. Antonelli</a>, <a href="/search/astro-ph?searchtype=author&query=Arcaro%2C+C">C. Arcaro</a>, <a href="/search/astro-ph?searchtype=author&query=Baack%2C+D">D. Baack</a>, <a href="/search/astro-ph?searchtype=author&query=Babi%C4%87%2C+A">A. Babi膰</a>, <a href="/search/astro-ph?searchtype=author&query=Banerjee%2C+B">B. Banerjee</a>, <a href="/search/astro-ph?searchtype=author&query=Bangale%2C+P">P. Bangale</a>, <a href="/search/astro-ph?searchtype=author&query=de+Almeida%2C+U+B">U. Barres de Almeida</a>, <a href="/search/astro-ph?searchtype=author&query=Barrio%2C+J+A">J. A. Barrio</a>, <a href="/search/astro-ph?searchtype=author&query=Gonz%C3%A1lez%2C+J+B">J. Becerra Gonz谩lez</a>, <a href="/search/astro-ph?searchtype=author&query=Bednarek%2C+W">W. Bednarek</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardini%2C+E">E. Bernardini</a>, <a href="/search/astro-ph?searchtype=author&query=Berse%2C+R+C">R. Ch. Berse</a>, <a href="/search/astro-ph?searchtype=author&query=Berti%2C+A">A. Berti</a>, <a href="/search/astro-ph?searchtype=author&query=Bhattacharyya%2C+W">W. Bhattacharyya</a>, <a href="/search/astro-ph?searchtype=author&query=Biland%2C+A">A. Biland</a>, <a href="/search/astro-ph?searchtype=author&query=Blanch%2C+O">O. Blanch</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">G. Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Carosi%2C+R">R. Carosi</a>, <a href="/search/astro-ph?searchtype=author&query=Carosi%2C+A">A. Carosi</a>, <a href="/search/astro-ph?searchtype=author&query=Ceribella%2C+G">G. Ceribella</a>, <a href="/search/astro-ph?searchtype=author&query=Chatterjee%2C+A">A. Chatterjee</a>, <a href="/search/astro-ph?searchtype=author&query=Colak%2C+S+M">S. M. Colak</a> , et al. (165 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1807.00413v1-abstract-short" style="display: inline;"> The BL Lac object S5~0716+714, a highly variable blazar, underwent an impressive outburst in January 2015 (Phase A), followed by minor activity in February (Phase B). The MAGIC observations were triggered by the optical flux observed in Phase A, corresponding to the brightest ever reported state of the source in the R-band. The comprehensive dataset collected is investigated in order to shed light… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1807.00413v1-abstract-full').style.display = 'inline'; document.getElementById('1807.00413v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1807.00413v1-abstract-full" style="display: none;"> The BL Lac object S5~0716+714, a highly variable blazar, underwent an impressive outburst in January 2015 (Phase A), followed by minor activity in February (Phase B). The MAGIC observations were triggered by the optical flux observed in Phase A, corresponding to the brightest ever reported state of the source in the R-band. The comprehensive dataset collected is investigated in order to shed light on the mechanism of the broadband emission. Multi-wavelength light curves have been studied together with the broadband Spectral Energy Distributions (SEDs). The data set collected spans from radio, optical photometry and polarimetry, X-ray, high-energy (HE, 0.1 GeV < E < 100 GeV) with \textit{Fermi}-LAT to the very-high-energy (VHE, E>100 GeV) with MAGIC. The flaring state of Phase A was detected in all the energy bands, providing for the first time a multi-wavelength sample of simultaneous data from the radio band to the VHE. In the constructed SED the \textit{Swift}-XRT+\textit{NuSTAR} data constrain the transition between the synchrotron and inverse Compton components very accurately, while the second peak is constrained from 0.1~GeV to 600~GeV by \textit{Fermi}+MAGIC data. The broadband SED cannot be described with a one-zone synchrotron self-Compton model as it severely underestimates the optical flux in order to reproduce the X-ray to $纬$-ray data. Instead we use a two-zone model. The EVPA shows an unprecedented fast rotation. An estimation of the redshift of the source by combined HE and VHE data provides a value of $z = 0.31 \pm 0.02_{stats} \pm 0.05_{sys}$, confirming the literature value. The data show the VHE emission originating in the entrance and exit of a superluminal knot in and out a recollimation shock in the inner jet. A shock-shock interaction in the jet seems responsible for the observed flares and EVPA swing. This scenario is also consistent with the SED modelling. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1807.00413v1-abstract-full').style.display = 'none'; document.getElementById('1807.00413v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 July, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Astronomy & Astrophysics 619, A45 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1806.05367">arXiv:1806.05367</a> <span> [<a href="https://arxiv.org/pdf/1806.05367">pdf</a>, <a href="https://arxiv.org/ps/1806.05367">ps</a>, <a href="https://arxiv.org/format/1806.05367">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201833618">10.1051/0004-6361/201833618 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Detection of persistent VHE gamma-ray emission from PKS 1510-089 by the MAGIC telescopes during low states between 2012 and 2017 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=MAGIC+Collaboration"> MAGIC Collaboration</a>, <a href="/search/astro-ph?searchtype=author&query=Acciari%2C+V+A">V. A. Acciari</a>, <a href="/search/astro-ph?searchtype=author&query=Ansoldi%2C+S">S. Ansoldi</a>, <a href="/search/astro-ph?searchtype=author&query=Antonelli%2C+L+A">L. A. Antonelli</a>, <a href="/search/astro-ph?searchtype=author&query=Engels%2C+A+A">A. Arbet Engels</a>, <a href="/search/astro-ph?searchtype=author&query=Arcaro%2C+C">C. Arcaro</a>, <a href="/search/astro-ph?searchtype=author&query=Baack%2C+D">D. Baack</a>, <a href="/search/astro-ph?searchtype=author&query=Babi%C4%87%2C+A">A. Babi膰</a>, <a href="/search/astro-ph?searchtype=author&query=Banerjee%2C+B">B. Banerjee</a>, <a href="/search/astro-ph?searchtype=author&query=Bangale%2C+P">P. Bangale</a>, <a href="/search/astro-ph?searchtype=author&query=de+Almeida%2C+U+B">U. Barres de Almeida</a>, <a href="/search/astro-ph?searchtype=author&query=Barrio%2C+J+A">J. A. Barrio</a>, <a href="/search/astro-ph?searchtype=author&query=Gonz%C3%A1lez%2C+J+B">J. Becerra Gonz谩lez</a>, <a href="/search/astro-ph?searchtype=author&query=Bednarek%2C+W">W. Bednarek</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardini%2C+E">E. Bernardini</a>, <a href="/search/astro-ph?searchtype=author&query=Berti%2C+A">A. Berti</a>, <a href="/search/astro-ph?searchtype=author&query=Besenrieder%2C+J">J. Besenrieder</a>, <a href="/search/astro-ph?searchtype=author&query=Bhattacharyya%2C+W">W. Bhattacharyya</a>, <a href="/search/astro-ph?searchtype=author&query=Bigongiari%2C+C">C. Bigongiari</a>, <a href="/search/astro-ph?searchtype=author&query=Biland%2C+A">A. Biland</a>, <a href="/search/astro-ph?searchtype=author&query=Blanch%2C+O">O. Blanch</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">G. Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Carosi%2C+R">R. Carosi</a>, <a href="/search/astro-ph?searchtype=author&query=Ceribella%2C+G">G. Ceribella</a>, <a href="/search/astro-ph?searchtype=author&query=Chatterjee%2C+A">A. Chatterjee</a> , et al. (143 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1806.05367v2-abstract-short" style="display: inline;"> PKS 1510-089 is a flat spectrum radio quasar strongly variable in the optical and GeV range. We search for low-state VHE gamma-ray emission from PKS 1510-089. We aim to characterize and model the source in a broad-band context, which would provide a baseline over which high states and flares could be better understood. We use daily binned Fermi-LAT flux measurements of PKS 1510-089 to characterize… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1806.05367v2-abstract-full').style.display = 'inline'; document.getElementById('1806.05367v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1806.05367v2-abstract-full" style="display: none;"> PKS 1510-089 is a flat spectrum radio quasar strongly variable in the optical and GeV range. We search for low-state VHE gamma-ray emission from PKS 1510-089. We aim to characterize and model the source in a broad-band context, which would provide a baseline over which high states and flares could be better understood. We use daily binned Fermi-LAT flux measurements of PKS 1510-089 to characterize the GeV emission and select the observation periods of MAGIC during low state of activity. For the selected times we compute the average radio, IR, optical, UV, X-ray and gamma-ray emission to construct a low-state spectral energy distribution of the source. The broadband emission is modelled within an External Compton scenario with a stationary emission region through which plasma and magnetic field are flowing. We perform also the emission-model-independent calculations of the maximum absorption in the broad line region (BLR) using two different models. Results. The MAGIC telescopes collected 75 hrs of data during times when the Fermi-LAT flux measured above 1 GeV was below 3x10-8cm-2s-1, which is the threshold adopted for the definition of a low gamma-ray activity state. The data show a strongly significant (9.5蟽) VHE gamma-ray emission at the level of (4.27+-0.61stat)x10-12cm-2s-1 above 150GeV, a factor 80 smaller than the highest flare observed so far from this object. Despite the lower flux, the spectral shape is consistent with earlier detections in the VHE band. The broad-band emission is compatible with the EC scenario assuming a large emission region located beyond the BLR. For the first time the gamma-ray data allow us to place a limit on the location of the emission region during a low gamma-ray state of a FSRQ. For the used model of the BLR, the 95% C.L. on the location of the emission region allows us to place it at the distance >74% of the outer radius of the BLR. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1806.05367v2-abstract-full').style.display = 'none'; document.getElementById('1806.05367v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 September, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 June, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 7 figures, accepted for publication in A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 619, A159 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1805.04723">arXiv:1805.04723</a> <span> [<a href="https://arxiv.org/pdf/1805.04723">pdf</a>, <a href="https://arxiv.org/ps/1805.04723">ps</a>, <a href="https://arxiv.org/format/1805.04723">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/aab785">10.3847/1538-4357/aab785 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Exploring the connection between parsec-scale jet activity and broadband outbursts in 3C 279 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Rani%2C+B">B. Rani</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">S. G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">A. P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">I. Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Sokolovsky%2C+K+V">K. V. Sokolovsky</a>, <a href="/search/astro-ph?searchtype=author&query=Larionov%2C+V+M">V. M. Larionov</a>, <a href="/search/astro-ph?searchtype=author&query=Smith%2C+P">P. Smith</a>, <a href="/search/astro-ph?searchtype=author&query=Mosunova%2C+D+A">D. A. Mosunova</a>, <a href="/search/astro-ph?searchtype=author&query=Borman%2C+G+A">G. A. Borman</a>, <a href="/search/astro-ph?searchtype=author&query=Grishina%2C+T+S">T. S. Grishina</a>, <a href="/search/astro-ph?searchtype=author&query=Kopatskaya%2C+E+N">E. N. Kopatskaya</a>, <a href="/search/astro-ph?searchtype=author&query=Mokrushina%2C+A+A">A. A. Mokrushina</a>, <a href="/search/astro-ph?searchtype=author&query=Morozova%2C+D+A">D. A. Morozova</a>, <a href="/search/astro-ph?searchtype=author&query=Savchenko%2C+S+S">S. S. Savchenko</a>, <a href="/search/astro-ph?searchtype=author&query=Troitskaya%2C+Y+V">Yu. V. Troitskaya</a>, <a href="/search/astro-ph?searchtype=author&query=Troitsky%2C+I+S">I. S. Troitsky</a>, <a href="/search/astro-ph?searchtype=author&query=Thum%2C+C">C. Thum</a>, <a href="/search/astro-ph?searchtype=author&query=Molina%2C+S+N">S. N. Molina</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">C. Casadio</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1805.04723v2-abstract-short" style="display: inline;"> We use a combination of high-resolution very long baseline interferometry (VLBI) radio and multi-wavelength flux density and polarization observations to constrain the physics of the dissipation mechanism powering the broadband flares in 3C 279 during an episode of extreme flaring activity in 2013-2014. Six bright flares superimposed on a long-term outburst are detected at $纬$-ray energies. Four o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1805.04723v2-abstract-full').style.display = 'inline'; document.getElementById('1805.04723v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1805.04723v2-abstract-full" style="display: none;"> We use a combination of high-resolution very long baseline interferometry (VLBI) radio and multi-wavelength flux density and polarization observations to constrain the physics of the dissipation mechanism powering the broadband flares in 3C 279 during an episode of extreme flaring activity in 2013-2014. Six bright flares superimposed on a long-term outburst are detected at $纬$-ray energies. Four of the flares have optical and radio counterparts. The two modes of flaring activity (faster flares sitting on top of a long term outburst) present at radio, optical, $纬$-ray frequencies are missing in X-rays. X-ray counterparts are only observed for two flares. The first three flares are accompanied by ejection of a new VLBI component (NC2) suggesting the 43 GHz VLBI core as the site of energy dissipation. Another new component, NC3, is ejected after the last three flares, which suggests that the emission is produced upstream from the core (closer to the black hole). The study therefore indicates multiple sites of energy dissipation in the source. An anti-correlation is detected between the optical percentage polarization (PP) and optical/$纬$-ray flux variations, while the PP has a positive correlation with optical/$纬$-rays spectral indices. Given that the mean polarization is inversely proportional to the number of cells in the emission region, the PP vs. optical/$纬$-ray anti-correlation could be due to more active cells during the outburst than at other times. In addition to the turbulent component, our analysis suggests the presence of a combined turbulent and ordered magnetic field, with the ordered component transverse to the jet axis. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1805.04723v2-abstract-full').style.display = 'none'; document.getElementById('1805.04723v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 May, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 12 May, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">ApJ (in press), 14 pages, 19 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1801.04138">arXiv:1801.04138</a> <span> [<a href="https://arxiv.org/pdf/1801.04138">pdf</a>, <a href="https://arxiv.org/ps/1801.04138">ps</a>, <a href="https://arxiv.org/format/1801.04138">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201832624">10.1051/0004-6361/201832624 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The detection of the blazar S4 0954+65 at very-high-energy with the MAGIC telescopes during an exceptionally high optical state </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=MAGIC+Collaboration"> MAGIC Collaboration</a>, <a href="/search/astro-ph?searchtype=author&query=Ahnen%2C+M+L">M. L. Ahnen</a>, <a href="/search/astro-ph?searchtype=author&query=Ansoldi%2C+S">S. Ansoldi</a>, <a href="/search/astro-ph?searchtype=author&query=Antonelli%2C+L+A">L. A. Antonelli</a>, <a href="/search/astro-ph?searchtype=author&query=Arcaro%2C+C">C. Arcaro</a>, <a href="/search/astro-ph?searchtype=author&query=Baack%2C+D">D. Baack</a>, <a href="/search/astro-ph?searchtype=author&query=Babi%C4%87%2C+A">A. Babi膰</a>, <a href="/search/astro-ph?searchtype=author&query=Banerjee%2C+B">B. Banerjee</a>, <a href="/search/astro-ph?searchtype=author&query=Bangale%2C+P">P. Bangale</a>, <a href="/search/astro-ph?searchtype=author&query=de+Almeida%2C+U+B">U. Barres de Almeida</a>, <a href="/search/astro-ph?searchtype=author&query=Barrio%2C+J+A">J. A. Barrio</a>, <a href="/search/astro-ph?searchtype=author&query=Bednarek%2C+W">W. Bednarek</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardini%2C+E">E. Bernardini</a>, <a href="/search/astro-ph?searchtype=author&query=Berse%2C+R+C">R. Ch. Berse</a>, <a href="/search/astro-ph?searchtype=author&query=Berti%2C+A">A. Berti</a>, <a href="/search/astro-ph?searchtype=author&query=Bhattacharyya%2C+W">W. Bhattacharyya</a>, <a href="/search/astro-ph?searchtype=author&query=Biland%2C+A">A. Biland</a>, <a href="/search/astro-ph?searchtype=author&query=Blanch%2C+O">O. Blanch</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">G. Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Carosi%2C+R">R. Carosi</a>, <a href="/search/astro-ph?searchtype=author&query=Carosi%2C+A">A. Carosi</a>, <a href="/search/astro-ph?searchtype=author&query=Ceribella%2C+G">G. Ceribella</a>, <a href="/search/astro-ph?searchtype=author&query=Chatterjee%2C+A">A. Chatterjee</a>, <a href="/search/astro-ph?searchtype=author&query=Colak%2C+S+M">S. M. Colak</a>, <a href="/search/astro-ph?searchtype=author&query=Colin%2C+P">P. Colin</a> , et al. (147 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1801.04138v1-abstract-short" style="display: inline;"> The very-high-energy (VHE, $\gtrsim 100$ GeV) $纬$-ray MAGIC observations of the blazar S4 0954+65, were triggered by an exceptionally high flux state of emission in the optical. This blazar has a disputed redshift of z=0.368 or z$\geqslant$0.45 and an uncertain classification among blazar subclasses. The exceptional source state described here makes for an excellent opportunity to understand physi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1801.04138v1-abstract-full').style.display = 'inline'; document.getElementById('1801.04138v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1801.04138v1-abstract-full" style="display: none;"> The very-high-energy (VHE, $\gtrsim 100$ GeV) $纬$-ray MAGIC observations of the blazar S4 0954+65, were triggered by an exceptionally high flux state of emission in the optical. This blazar has a disputed redshift of z=0.368 or z$\geqslant$0.45 and an uncertain classification among blazar subclasses. The exceptional source state described here makes for an excellent opportunity to understand physical processes in the jet of S4 0954+65 and thus contribute to its classification. We investigate the multiwavelength (MWL) light curve and spectral energy distribution (SED) of the S4 0954+65 blazar during an enhanced state in February 2015 and put it in context with possible emission scenarios. We collect photometric data in radio, optical, X-ray, and $纬$ ray. We study both the optical polarization and the inner parsec-scale jet behavior with 43 GHz data. Observations with the MAGIC telescopes led to the first detection of S4 0954+65 at VHE. Simultaneous data with Fermi-LAT at high energy $纬$ ray\ (HE, 100 MeV < E < 100 GeV) also show a period of increased activity. Imaging at 43 GHz reveals the emergence of a new feature in the radio jet in coincidence with the VHE flare. Simultaneous monitoring of the optical polarization angle reveals a rotation of approximately 100$^\circ$. (...) The broadband spectrum can be modeled with an emission mechanism commonly invoked for flat spectrum radio quasars, i.e. inverse Compton scattering on an external soft photon field from the dust torus, also known as external Compton. The light curve and SED phenomenology is consistent with an interpretation of a blob propagating through a helical structured magnetic field and eventually crossing a standing shock in the jet, a scenario typically applied to flat spectrum radio quasars (FSRQs) and low-frequency peaked BL Lac objects (LBL). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1801.04138v1-abstract-full').style.display = 'none'; document.getElementById('1801.04138v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 January, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 7 figures, submitted to A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 617, A30 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1711.08461">arXiv:1711.08461</a> <span> [<a href="https://arxiv.org/pdf/1711.08461">pdf</a>, <a href="https://arxiv.org/format/1711.08461">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> </div> <p class="title is-5 mathjax"> 3 mm GMVA Observations of Total and Polarized Emission from Blazar and Radio Galaxy Core Regions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">Carolina Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Krichbaum%2C+T+P">Thomas P. Krichbaum</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Gomez%2C+J+L">Jose L. Gomez</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Ivan Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">Uwe Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+J">Jae-Young Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Hodgson%2C+J+A">Jeffrey A. Hodgson</a>, <a href="/search/astro-ph?searchtype=author&query=Zensus%2C+A+J">Anton J. Zensus</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1711.08461v1-abstract-short" style="display: inline;"> We present total and linearly polarized 3 mm Global mm-VLBI Array images of a sample of blazars and radio galaxies from the VLBA-BU-BLAZAR 7 mm monitoring program designed to probe the innermost regions of active galactic nuclei (AGN) jets and locate the sites of gamma-ray emission observed by the Fermi-LAT. The lower opacity at 3 mm and improved angular resolution, on the order of 50 microarcseco… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1711.08461v1-abstract-full').style.display = 'inline'; document.getElementById('1711.08461v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1711.08461v1-abstract-full" style="display: none;"> We present total and linearly polarized 3 mm Global mm-VLBI Array images of a sample of blazars and radio galaxies from the VLBA-BU-BLAZAR 7 mm monitoring program designed to probe the innermost regions of active galactic nuclei (AGN) jets and locate the sites of gamma-ray emission observed by the Fermi-LAT. The lower opacity at 3 mm and improved angular resolution, on the order of 50 microarcseconds, allow us to distinguish features in the jet not visible in the 7 mm VLBA data. We also compare two different methods used for the calibration of instrumental polarisation and we analyze the resulting images for some of the sources in the sample. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1711.08461v1-abstract-full').style.display = 'none'; document.getElementById('1711.08461v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 November, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Polarised Emission from Astrophysical Jets, June 12-16, 2017, Ierapetra, Greece</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1711.03983">arXiv:1711.03983</a> <span> [<a href="https://arxiv.org/pdf/1711.03983">pdf</a>, <a href="https://arxiv.org/ps/1711.03983">ps</a>, <a href="https://arxiv.org/format/1711.03983">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/aa8407">10.3847/1538-4357/aa8407 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Kinematics of Parsec-Scale Jets of Gamma-Ray Blazars at 43~GHz within the VLBA-BU-BLAZAR Program </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Morozova%2C+D+A">Daria A. Morozova</a>, <a href="/search/astro-ph?searchtype=author&query=Troitsky%2C+I+S">Ivan S. Troitsky</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">Carolina Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Foord%2C+A">Adi Foord</a>, <a href="/search/astro-ph?searchtype=author&query=G%C3%B3mez%2C+J+L">Jos茅 L. G贸mez</a>, <a href="/search/astro-ph?searchtype=author&query=MacDonald%2C+N+R">Nicholas R. MacDonald</a>, <a href="/search/astro-ph?searchtype=author&query=Molina%2C+S+N">Sol N. Molina</a>, <a href="/search/astro-ph?searchtype=author&query=L%C3%A4hteenm%C3%A4ki%2C+A">Anne L盲hteenm盲ki</a>, <a href="/search/astro-ph?searchtype=author&query=Tammi%2C+J">Joni Tammi</a>, <a href="/search/astro-ph?searchtype=author&query=Tornikoski%2C+M">Merja Tornikoski</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1711.03983v1-abstract-short" style="display: inline;"> We analyze the parsec-scale jet kinematics from 2007 June to 2013 January of a sample of $纬$-ray bright blazars monitored roughly monthly with the Very Long Baseline Array at 43~GHz. In a total of 1929 images, we measure apparent speeds of 252 emission knots in 21 quasars, 12 BL~Lacertae objects (BLLacs), and 3 radio galaxies, ranging from 0.02$c$ to 78$c$; 21\% of the knots are quasi-stationary.… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1711.03983v1-abstract-full').style.display = 'inline'; document.getElementById('1711.03983v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1711.03983v1-abstract-full" style="display: none;"> We analyze the parsec-scale jet kinematics from 2007 June to 2013 January of a sample of $纬$-ray bright blazars monitored roughly monthly with the Very Long Baseline Array at 43~GHz. In a total of 1929 images, we measure apparent speeds of 252 emission knots in 21 quasars, 12 BL~Lacertae objects (BLLacs), and 3 radio galaxies, ranging from 0.02$c$ to 78$c$; 21\% of the knots are quasi-stationary. Approximately 1/3 of the moving knots execute non-ballistic motions, with the quasars exhibiting acceleration along the jet within 5~pc (projected) of the core, and knots in the BLLacs tending to decelerate near the core. Using apparent speeds of components and timescales of variability from their light curves, we derive physical parameters of 120 superluminal knots, including variability Doppler factors, Lorentz factors, and viewing angles. We estimate the half-opening angle of each jet based on the projected opening angle and scatter of intrinsic viewing angles of knots. We determine characteristic values of physical parameters for each jet and AGN class based on the range of values obtained for individual features. We calculate intrinsic brightness temperatures of the cores, $T_{\rm b,int}^{\rm core}$, at all epochs, finding that the radio galaxies usually maintain equipartition conditions in the cores, while $\sim$30\% of $T_{\rm b,int}^{\rm core}$ measurements in the quasars and BLLacs deviate from equipartition values by a factor $>$10. This probably occurs during transient events connected with active states. In the Appendix we briefly describe the behavior of each blazar during the period analyzed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1711.03983v1-abstract-full').style.display = 'none'; document.getElementById('1711.03983v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 November, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">48 pages, 18 figures, Tables 2,3,5, & 7 in a full length and figures 2 and 4 for each source can be found in the journal version of the paper</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> The Astrophysical Journal, Volume 846, Issue 2, article id. 98, 35 pp. (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1711.01593">arXiv:1711.01593</a> <span> [<a href="https://arxiv.org/pdf/1711.01593">pdf</a>, <a href="https://arxiv.org/format/1711.01593">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201731952">10.1051/0004-6361/201731952 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> VLBA polarimetric monitoring of 3C 111 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Beuchert%2C+T">T. Beuchert</a>, <a href="/search/astro-ph?searchtype=author&query=Kadler%2C+M">M. Kadler</a>, <a href="/search/astro-ph?searchtype=author&query=Perucho%2C+M">M. Perucho</a>, <a href="/search/astro-ph?searchtype=author&query=Gro%C3%9Fberger%2C+C">C. Gro脽berger</a>, <a href="/search/astro-ph?searchtype=author&query=Schulz%2C+R">R. Schulz</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">I. Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">C. Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=G%C3%B3mez%2C+J+L">J. L. G贸mez</a>, <a href="/search/astro-ph?searchtype=author&query=Gurwell%2C+M">M. Gurwell</a>, <a href="/search/astro-ph?searchtype=author&query=Homan%2C+D">D. Homan</a>, <a href="/search/astro-ph?searchtype=author&query=Kovalev%2C+Y+Y">Y. Y. Kovalev</a>, <a href="/search/astro-ph?searchtype=author&query=Lister%2C+M+L">M. L. Lister</a>, <a href="/search/astro-ph?searchtype=author&query=Markoff%2C+S">S. Markoff</a>, <a href="/search/astro-ph?searchtype=author&query=Molina%2C+S+N">S. N. Molina</a>, <a href="/search/astro-ph?searchtype=author&query=Pushkarev%2C+A+B">A. B. Pushkarev</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">E. Ros</a>, <a href="/search/astro-ph?searchtype=author&query=Savolainen%2C+T">T. Savolainen</a>, <a href="/search/astro-ph?searchtype=author&query=Steinbring%2C+T">T. Steinbring</a>, <a href="/search/astro-ph?searchtype=author&query=Thum%2C+C">C. Thum</a>, <a href="/search/astro-ph?searchtype=author&query=Wilms%2C+J">J. Wilms</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1711.01593v1-abstract-short" style="display: inline;"> We aim to better understand the dynamics within relativistic magneto-hydrodynamical flows in the extreme environment and close vicinity of supermassive black holes. To do so, we analyze the peculiar radio galaxy 3C 111, for which long-term polarimetric observations are available. We make use of the high spatial resolution of the VLBA network and the MOJAVE monitoring program, which provides high d… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1711.01593v1-abstract-full').style.display = 'inline'; document.getElementById('1711.01593v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1711.01593v1-abstract-full" style="display: none;"> We aim to better understand the dynamics within relativistic magneto-hydrodynamical flows in the extreme environment and close vicinity of supermassive black holes. To do so, we analyze the peculiar radio galaxy 3C 111, for which long-term polarimetric observations are available. We make use of the high spatial resolution of the VLBA network and the MOJAVE monitoring program, which provides high data quality also for single sources and allows us to study jet dynamics on parsec scales in full polarization with an evenly sampled time-domain. We additionally consider data from the IRAM 30-m Telescope as well as the SMA. Jet properties such as the electric vectors, the (polarized) flux density, feature size, and brightness temperature, describe a complex evolution of the polarized jet. The electric vector position angles (EVPAs) of features traveling down the jet perform a large and smooth rotation of $\gtrsim 180^{\circ}$ across a distance of about 20 pc. In contrast, the EVPAs are strongly variable within the first parsecs of the jet. We find a tendency towards transverse EVPAs across the jet with a local anomaly of aligned vectors in between. The transverse extent of the flow decreases coincident with a jump in brightness temperature around where we observe the EVPAs to turn into alignment with the jet flow. Also the gradients of the feature size and particle density with distance steepen in that region. We interpret the propagating polarized features with shocks and the observed local anomalies with the interaction of these shocks with a recollimation shock of the underlying flow. Together with a sheared magnetic field, this shock-shock interaction can explain the large rotation of the EVPA. The superimposed variability of the EVPAs close to the core is likely related to a clumpy Faraday screen, which also contributes significantly to the observed EVPA rotation in that region. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1711.01593v1-abstract-full').style.display = 'none'; document.getElementById('1711.01593v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 November, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 22 figures, 2 tables, accepted for publication by A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 610, A32 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1709.08744">arXiv:1709.08744</a> <span> [<a href="https://arxiv.org/pdf/1709.08744">pdf</a>, <a href="https://arxiv.org/ps/1709.08744">ps</a>, <a href="https://arxiv.org/format/1709.08744">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1093/mnras/stx2437">10.1093/mnras/stx2437 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> POLAMI: Polarimetric Monitoring of Active Galactic Nuclei at Millimetre Wavelengths. III. Characterisation of total flux density and polarisation variability of relativistic jets </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Ivan Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Thum%2C+C">Clemens Thum</a>, <a href="/search/astro-ph?searchtype=author&query=Ramakrishnan%2C+V">Venkatessh Ramakrishnan</a>, <a href="/search/astro-ph?searchtype=author&query=Molina%2C+S+N">Sol N. Molina</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">Carolina Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Gomez%2C+J+L">Jose L. Gomez</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1709.08744v1-abstract-short" style="display: inline;"> We report on the first results of the POLAMI program, a simultaneous 3.5 and 1.3mm full-Stokes-polarisation monitoring of a sample of 36 of the brightest active galactic nuclei in the northern sky with the IRAM 30m Telescope. Through a systematic statistical study of data taken from October 2006 (from December 2009 for the case of the 1.3mm observations) to August 2014, we characterise the variabi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1709.08744v1-abstract-full').style.display = 'inline'; document.getElementById('1709.08744v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1709.08744v1-abstract-full" style="display: none;"> We report on the first results of the POLAMI program, a simultaneous 3.5 and 1.3mm full-Stokes-polarisation monitoring of a sample of 36 of the brightest active galactic nuclei in the northern sky with the IRAM 30m Telescope. Through a systematic statistical study of data taken from October 2006 (from December 2009 for the case of the 1.3mm observations) to August 2014, we characterise the variability of the total flux density and linear polarisation. We find that all sources in the sample are highly variable in total flux density at both 3.5 and 1.3mm, as well as in spectral index, that is found to be optically thin in general. The total flux-density variability at 1.3mm is found, in general, to be faster, and to have larger amplitude and flatter PSD slopes than 3.5mm. The polarisation degree is on average larger at 1.3mm than at 3.5mm, by a factor of 2.6. The variability of linear polarisation degree is faster and has higher fractional amplitude than for total flux density, with the typical time scales during prominent polarisation peaks being significantly faster at 1.3mm than at 3.5mm. The polarisation angle at both 3.5 and 1.3mm is highly variable. Most of the sources show one or two excursions of >180 deg. on time scales from a few weeks to about a year during the course of our observations. The 3.5 and 1.3mm polarisation angle evolution follow rather well each other, although the 1.3mm data show a clear preference to more prominent variability on the short time scales, i.e. weeks. The data are compatible with multi-zone models of conical jets involving smaller emission regions for the shortest-wavelength emitting sites. Such smaller emitting regions should also be more efficient in energising particle populations. The data also favours the integrated emission at 1.3mm to have better ordered magnetic fields than the one at 3.5mm. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1709.08744v1-abstract-full').style.display = 'none'; document.getElementById('1709.08744v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 September, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in MNRAS. 36 pages, 11 figures, and 6 tables</span> </p> </li> </ol> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a 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