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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=Bach%2C+U&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Bach%2C+U&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Bach%2C+U&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> <li> <a href="/search/?searchtype=author&query=Bach%2C+U&start=100" class="pagination-link " aria-label="Page 3" aria-current="page">3 </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/2501.12168">arXiv:2501.12168</a> <span> [<a href="https://arxiv.org/pdf/2501.12168">pdf</a>, <a href="https://arxiv.org/ps/2501.12168">ps</a>, <a href="https://arxiv.org/format/2501.12168">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"> Investigating launching of black hole jets with the combined power of the EVN and the EHT </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Paraschos%2C+G+F">G. F. Paraschos</a>, <a href="/search/astro-ph?searchtype=author&query=Debbrecht%2C+L+C">L. C. Debbrecht</a>, <a href="/search/astro-ph?searchtype=author&query=Kramer%2C+J+A">J. A. Kramer</a>, <a href="/search/astro-ph?searchtype=author&query=Traianou%2C+E">E. Traianou</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">I. Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Krichbaum%2C+T">T. Krichbaum</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+J+-">J. -Y. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Janssen%2C+M">M. Janssen</a>, <a href="/search/astro-ph?searchtype=author&query=Nair%2C+D+G">D. G. Nair</a>, <a href="/search/astro-ph?searchtype=author&query=Savolainen%2C+T">T. Savolainen</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">E. Ros</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U Bach</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=Lisakov%2C+M">M. Lisakov</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=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="2501.12168v1-abstract-short" style="display: inline;"> AGN-launched jets are a crucial element in the study of supermassive black holes (SMBH) and their closest surroundings. The formation of such jets, whether they are launched by magnetic field lines anchored to the accretion disc or directly connected to the black hole's (BH) ergosphere, is the subject of ongoing, extensive research. 3C84, the compact radio source in the central galaxy NGC1275 of t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.12168v1-abstract-full').style.display = 'inline'; document.getElementById('2501.12168v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.12168v1-abstract-full" style="display: none;"> AGN-launched jets are a crucial element in the study of supermassive black holes (SMBH) and their closest surroundings. The formation of such jets, whether they are launched by magnetic field lines anchored to the accretion disc or directly connected to the black hole's (BH) ergosphere, is the subject of ongoing, extensive research. 3C84, the compact radio source in the central galaxy NGC1275 of the Perseus super-cluster, is a prime laboratory for testing such jet launching scenarios, as well as studying the innermost, sub-parsec AGN structure and jet origin. Very long baseline interferometry (VLBI) offers a unique view into the physical processes in action, in the immediate vicinity of BHs, unparalleled by other observational techniques. With VLBI at short wavelengths particular high angular resolutions are obtained. Utilising such cm and mm-VLBI observations of 3C84 with the European VLBI Network and the Event Horizon Telescope, we study the magnetic field strength and associated accretion flow around its central SMBH. This is possible, as higher frequency VLBI measurements are capable of peering through the accretion flow surrounding the central engine of 3C84, which is known to block the line of sight to the sub-parsec counter-jet via free-free absorption. Furthermore, we study the magnetic field's signature in the core region, as manifested in polarised light. As part of this analysis we compare our observations to relativistic magneto-hydrodynamic simulations. Finally, we investigate the effect of instabilities on the shape of the jet's parsec-scale funnel and try to connect them to its historical evolution. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.12168v1-abstract-full').style.display = 'none'; document.getElementById('2501.12168v1-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 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">4 pages, 4 figures, Proceedings of the 16th European VLBI Network Symposium</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2501.08685">arXiv:2501.08685</a> <span> [<a href="https://arxiv.org/pdf/2501.08685">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> </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/10.1051/0004-6361/202450898">10.1051/0004-6361/202450898 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The putative center in NGC 1052 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Baczko%2C+A">Anne-Kathrin Baczko</a>, <a href="/search/astro-ph?searchtype=author&query=Kadler%2C+M">Matthias Kadler</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">Eduardo Ros</a>, <a href="/search/astro-ph?searchtype=author&query=Fromm%2C+C+M">Christian M. Fromm</a>, <a href="/search/astro-ph?searchtype=author&query=Wielgus%2C+M">Maciek Wielgus</a>, <a href="/search/astro-ph?searchtype=author&query=Perucho%2C+M">Manel Perucho</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=Balokovi%C4%87%2C+M">Mislav Balokovi膰</a>, <a href="/search/astro-ph?searchtype=author&query=Blackburn%2C+L">Lindy Blackburn</a>, <a href="/search/astro-ph?searchtype=author&query=Chan%2C+C">Chi-kwan Chan</a>, <a href="/search/astro-ph?searchtype=author&query=Issaoun%2C+S">Sara Issaoun</a>, <a href="/search/astro-ph?searchtype=author&query=Janssen%2C+M">Michael Janssen</a>, <a href="/search/astro-ph?searchtype=author&query=Ricci%2C+L">Luca Ricci</a>, <a href="/search/astro-ph?searchtype=author&query=Akiyama%2C+K">Kazunori Akiyama</a>, <a href="/search/astro-ph?searchtype=author&query=Albentosa-Ru%C3%ADz%2C+E">Ezequiel Albentosa-Ru铆z</a>, <a href="/search/astro-ph?searchtype=author&query=Alberdi%2C+A">Antxon Alberdi</a>, <a href="/search/astro-ph?searchtype=author&query=Alef%2C+W">Walter Alef</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=Anantua%2C+R">Richard Anantua</a>, <a href="/search/astro-ph?searchtype=author&query=Asada%2C+K">Keiichi Asada</a>, <a href="/search/astro-ph?searchtype=author&query=Azulay%2C+R">Rebecca Azulay</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">Uwe Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Ball%2C+D">David Ball</a>, <a href="/search/astro-ph?searchtype=author&query=Bandyopadhyay%2C+B">Bidisha Bandyopadhyay</a>, <a href="/search/astro-ph?searchtype=author&query=Barrett%2C+J">John Barrett</a> , et al. (262 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="2501.08685v1-abstract-short" style="display: inline;"> Many active galaxies harbor powerful relativistic jets, however, the detailed mechanisms of their formation and acceleration remain poorly understood. To investigate the area of jet acceleration and collimation with the highest available angular resolution, we study the innermost region of the bipolar jet in the nearby low-ionization nuclear emission-line region (LINER) galaxy NGC 1052. We combine… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.08685v1-abstract-full').style.display = 'inline'; document.getElementById('2501.08685v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.08685v1-abstract-full" style="display: none;"> Many active galaxies harbor powerful relativistic jets, however, the detailed mechanisms of their formation and acceleration remain poorly understood. To investigate the area of jet acceleration and collimation with the highest available angular resolution, we study the innermost region of the bipolar jet in the nearby low-ionization nuclear emission-line region (LINER) galaxy NGC 1052. We combined observations of NGC 1052 taken with VLBA, GMVA, and EHT over one week in the spring of 2017. For the first time, NGC 1052 was detected with the EHT, providing a size of the central region in-between both jet bases of 250 RS (Schwarzschild radii) perpendicular to the jet axes. This size estimate supports previous studies of the jets expansion profile which suggest two breaks of the profile at around 300 RS and 10000 RS distances to the core. Furthermore, we estimated the magnetic field to be 1.25 Gauss at a distance of 22 渭as from the central engine by fitting a synchrotron-self absorption spectrum to the innermost emission feature, which shows a spectral turn-over at about 130 GHz. Assuming a purely poloidal magnetic field, this implies an upper limit on the magnetic field strength at the event horizon of 26000 Gauss, which is consistent with previous measurements. The complex, low-brightness, double-sided jet structure in NGC 1052 makes it a challenge to detect the source at millimeter (mm) wavelengths. However, our first EHT observations have demonstrated that detection is possible up to at least 230 GHz. This study offers a glimpse through the dense surrounding torus and into the innermost central region, where the jets are formed. This has enabled us to finally resolve this region and provide improved constraints on its expansion and magnetic field strength. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.08685v1-abstract-full').style.display = 'none'; document.getElementById('2501.08685v1-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 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">22 pages, 10 figures, published 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, 692, A205 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2501.05518">arXiv:2501.05518</a> <span> [<a href="https://arxiv.org/pdf/2501.05518">pdf</a>, <a href="https://arxiv.org/format/2501.05518">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> </div> <p class="title is-5 mathjax"> A multi-frequency study of sub-parsec jets with the Event Horizon Telescope </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=R%C3%B6der%2C+J">Jan R枚der</a>, <a href="/search/astro-ph?searchtype=author&query=Wielgus%2C+M">Maciek Wielgus</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=Krichbaum%2C+T+P">Thomas P. Krichbaum</a>, <a href="/search/astro-ph?searchtype=author&query=Nair%2C+D+G">Dhanya G. Nair</a>, <a href="/search/astro-ph?searchtype=author&query=Lee%2C+S">Sang-Sung Lee</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">Eduardo Ros</a>, <a href="/search/astro-ph?searchtype=author&query=Fish%2C+V+L">Vincent L. Fish</a>, <a href="/search/astro-ph?searchtype=author&query=Blackburn%2C+L">Lindy Blackburn</a>, <a href="/search/astro-ph?searchtype=author&query=Chan%2C+C">Chi-kwan Chan</a>, <a href="/search/astro-ph?searchtype=author&query=Issaoun%2C+S">Sara Issaoun</a>, <a href="/search/astro-ph?searchtype=author&query=Janssen%2C+M">Michael Janssen</a>, <a href="/search/astro-ph?searchtype=author&query=Johnson%2C+M+D">Michael D. Johnson</a>, <a href="/search/astro-ph?searchtype=author&query=Doeleman%2C+S+S">Sheperd S. Doeleman</a>, <a href="/search/astro-ph?searchtype=author&query=Bower%2C+G+C">Geoffrey C. Bower</a>, <a href="/search/astro-ph?searchtype=author&query=Crew%2C+G+B">Geoffrey B. Crew</a>, <a href="/search/astro-ph?searchtype=author&query=Tilanus%2C+R+P+J">Remo P. J. Tilanus</a>, <a href="/search/astro-ph?searchtype=author&query=Savolainen%2C+T">Tuomas Savolainen</a>, <a href="/search/astro-ph?searchtype=author&query=Impellizzeri%2C+C+M+V">C. M. Violette Impellizzeri</a>, <a href="/search/astro-ph?searchtype=author&query=Alberdi%2C+A">Antxon Alberdi</a>, <a href="/search/astro-ph?searchtype=author&query=Baczko%2C+A">Anne-Kathrin Baczko</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=Lu%2C+R">Ru-Sen Lu</a>, <a href="/search/astro-ph?searchtype=author&query=Paraschos%2C+G+F">Georgios F. Paraschos</a>, <a href="/search/astro-ph?searchtype=author&query=Traianou%2C+E">Efthalia Traianou</a> , et al. (265 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="2501.05518v1-abstract-short" style="display: inline;"> The 2017 observing campaign of the Event Horizon Telescope (EHT) delivered the first very long baseline interferometry (VLBI) images at the observing frequency of 230 GHz, leading to a number of unique studies on black holes and relativistic jets from active galactic nuclei (AGN). In total, eighteen sources were observed: the main science targets, Sgr A* and M87 along with various calibrators. We… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.05518v1-abstract-full').style.display = 'inline'; document.getElementById('2501.05518v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.05518v1-abstract-full" style="display: none;"> The 2017 observing campaign of the Event Horizon Telescope (EHT) delivered the first very long baseline interferometry (VLBI) images at the observing frequency of 230 GHz, leading to a number of unique studies on black holes and relativistic jets from active galactic nuclei (AGN). In total, eighteen sources were observed: the main science targets, Sgr A* and M87 along with various calibrators. We investigated the morphology of the sixteen AGN in the EHT 2017 data set, focusing on the properties of the VLBI cores: size, flux density, and brightness temperature. We studied their dependence on the observing frequency in order to compare it with the Blandford-K枚nigl (BK) jet model. We modeled the source structure of seven AGN in the EHT 2017 data set using linearly polarized circular Gaussian components and collected results for the other nine AGN from dedicated EHT publications, complemented by lower frequency data in the 2-86 GHz range. Then, we studied the dependences of the VLBI core flux density, size, and brightness temperature on the frequency measured in the AGN host frame. We compared the observations with the BK jet model and estimated the magnetic field strength dependence on the distance from the central black hole. Our results indicate a deviation from the standard BK model, particularly in the decrease of the brightness temperature with the observing frequency. Either bulk acceleration of the jet material, energy transfer from the magnetic field to the particles, or both are required to explain the observations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.05518v1-abstract-full').style.display = 'none'; document.getElementById('2501.05518v1-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, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2025. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2412.19268">arXiv:2412.19268</a> <span> [<a href="https://arxiv.org/pdf/2412.19268">pdf</a>, <a href="https://arxiv.org/format/2412.19268">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"> Jet formation studies in AGN: a search for new targets </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=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=Bartolini%2C+V">V. Bartolini</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Grandi%2C+P">P. Grandi</a>, <a href="/search/astro-ph?searchtype=author&query=Torresi%2C+E">E. Torresi</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=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="2412.19268v1-abstract-short" style="display: inline;"> In recent years, the jet formation region in active galaxies has been imaged through mm-VLBI in few ideal targets, first and foremost M87. An important leap forward for understanding jet launching could be made by identifying a larger number of suitable objects, characterized by different accretion modes and jet powers. In this article, we present 1 cm and 7 mm VLBI data of a sample of 16 poorly e… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.19268v1-abstract-full').style.display = 'inline'; document.getElementById('2412.19268v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2412.19268v1-abstract-full" style="display: none;"> In recent years, the jet formation region in active galaxies has been imaged through mm-VLBI in few ideal targets, first and foremost M87. An important leap forward for understanding jet launching could be made by identifying a larger number of suitable objects, characterized by different accretion modes and jet powers. In this article, we present 1 cm and 7 mm VLBI data of a sample of 16 poorly explored radio galaxies, comprising both High-Excitation (HEG) and Low-Excitation Galaxies (LEG) and spanning a large range in radio power. The combination of the sources vicinity (z<0.1) with a large black hole mass ($\log{M_{\rm BH}}$>8.5) results in a high spatial resolution in units of Schwarzschild radii ($<10^3-10^4$ $R_{\rm S}$), necessary for probing the region where the jet is initially accelerated and collimated. We aim at identifying the best candidates for follow-up observations with current and future VLBI facilities. The observations were performed with the High Sensitivity Array, including Effelsberg and the phased-VLA, which has allowed us to characterize the sub-parsec properties of these faint jets and to estimate their core brightness temperature and orientation. The number of sources imaged on scales $\lesssim 10^3$ $R_{\rm S}$ is more than doubled by our study. All targets were detected at both frequencies, and several present two-sided jet structures. Several LEG jets show hints of limb-brightening. The core brightness temperatures are generally below the equipartition value, indicating that equipartition has not yet been reached and/or that the emission is de-boosted. Among LEG, we identify 3C31, 3C66B, and 3C465 as the most promising, combining a relatively high flux density (>50 mJy) with superb spatial resolution (<500 $R_{\rm S}$) at 7 mm. The powerful HEG 3C452 is interesting as well due to its highly symmetric, two-sided jet base. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2412.19268v1-abstract-full').style.display = 'none'; document.getElementById('2412.19268v1-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 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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">Main: 7 pages, 2 figures. Appendix: 15 pages, 15 figures. Accepted 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/2411.03446">arXiv:2411.03446</a> <span> [<a href="https://arxiv.org/pdf/2411.03446">pdf</a>, <a href="https://arxiv.org/format/2411.03446">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/10.1051/0004-6361/202449636">10.1051/0004-6361/202449636 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Kilogauss magnetic field and jet dynamics in the quasar NRAO 530 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Lisakov%2C+M">Mikhail Lisakov</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S">Svetlana Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Wielgus%2C+M">Maciek Wielgus</a>, <a href="/search/astro-ph?searchtype=author&query=Kravchenko%2C+E+V">Evgeniya V. Kravchenko</a>, <a href="/search/astro-ph?searchtype=author&query=Nikonov%2C+A+S">Aleksei S. Nikonov</a>, <a href="/search/astro-ph?searchtype=author&query=Cho%2C+I">Ilje Cho</a>, <a href="/search/astro-ph?searchtype=author&query=Issaoun%2C+S">Sara Issaoun</a>, <a href="/search/astro-ph?searchtype=author&query=Algaba%2C+J">Juan-Carlos Algaba</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=Bach%2C+U">Uwe Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">Eduardo Ros</a>, <a href="/search/astro-ph?searchtype=author&query=Rottmann%2C+H">Helge Rottmann</a>, <a href="/search/astro-ph?searchtype=author&query=S%27anchez%2C+S">Salvador S'anchez</a>, <a href="/search/astro-ph?searchtype=author&query=Wagner%2C+J">Jan Wagner</a>, <a href="/search/astro-ph?searchtype=author&query=Zensus%2C+A">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="2411.03446v1-abstract-short" style="display: inline;"> The advancement of the Event Horizon Telescope has enabled the study of relativistic jets in active galactic nuclei down to sub-parsec linear scales even at high redshift. Quasi-simultaneous multifrequency observations provide insights into the physical conditions in compact regions and allow testing accretion theories. Initially we aimed at measuring the magnetic field strength close to the centr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.03446v1-abstract-full').style.display = 'inline'; document.getElementById('2411.03446v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.03446v1-abstract-full" style="display: none;"> The advancement of the Event Horizon Telescope has enabled the study of relativistic jets in active galactic nuclei down to sub-parsec linear scales even at high redshift. Quasi-simultaneous multifrequency observations provide insights into the physical conditions in compact regions and allow testing accretion theories. Initially we aimed at measuring the magnetic field strength close to the central supermassive black hole in NRAO 530 (1730-130) by studying frequency-dependent opacity of the jet matter, Faraday rotation and the spectral index in the mm-radio bands. NRAO 530 was observed quasi-simultaneously at 15, 22, 43, 86, and 227 GHz at four different very long baseline interferometer (VLBI) networks. By the means of imaging and model-fitting, we aligned the images, taken at different frequencies. We explored opacity along the jet and distribution of the linearly polarized emission in it. Our findings reveal that the jet of NRAO 530 at 86 and 227 GHz is transparent down to its origin, with 70 mJy emission detected at 227 GHz potentially originating from the accretion disk. The magnetic field strength near the black hole, estimated at $5r_\mathrm{g}$, is $3\times10^3-3\times10^4$ G (depending on the central black hole mass). These values represent some of the highest magnetic field strengths reported for active galaxies. We also report the first ever VLBI measurement of the Faraday rotation at 43-227 GHz, which reveals rotation measure values as high as -48000 rad/m2 consistent with higher particle density and stronger magnetic fields at the jet's outset. The complex shape of the jet in NRAO 530 is in line with the expected behavior of a precessing jet, with a period estimated to be around $6\pm4$~years. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.03446v1-abstract-full').style.display = 'none'; document.getElementById('2411.03446v1-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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">18 pages, accepted 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 693, A9 (2025) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.07453">arXiv:2410.07453</a> <span> [<a href="https://arxiv.org/pdf/2410.07453">pdf</a>, <a href="https://arxiv.org/format/2410.07453">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> <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/10.3847/1538-3881/ad5bdb">10.3847/1538-3881/ad5bdb <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> First Very Long Baseline Interferometry Detections at 870渭m </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Raymond%2C+A+W">Alexander W. Raymond</a>, <a href="/search/astro-ph?searchtype=author&query=Doeleman%2C+S+S">Sheperd S. Doeleman</a>, <a href="/search/astro-ph?searchtype=author&query=Asada%2C+K">Keiichi Asada</a>, <a href="/search/astro-ph?searchtype=author&query=Blackburn%2C+L">Lindy Blackburn</a>, <a href="/search/astro-ph?searchtype=author&query=Bower%2C+G+C">Geoffrey C. Bower</a>, <a href="/search/astro-ph?searchtype=author&query=Bremer%2C+M">Michael Bremer</a>, <a href="/search/astro-ph?searchtype=author&query=Broguiere%2C+D">Dominique Broguiere</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+M">Ming-Tang Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Crew%2C+G+B">Geoffrey B. Crew</a>, <a href="/search/astro-ph?searchtype=author&query=Dornbusch%2C+S">Sven Dornbusch</a>, <a href="/search/astro-ph?searchtype=author&query=Fish%2C+V+L">Vincent L. Fish</a>, <a href="/search/astro-ph?searchtype=author&query=Garc%C3%ADa%2C+R">Roberto Garc铆a</a>, <a href="/search/astro-ph?searchtype=author&query=Gentaz%2C+O">Olivier Gentaz</a>, <a href="/search/astro-ph?searchtype=author&query=Goddi%2C+C">Ciriaco Goddi</a>, <a href="/search/astro-ph?searchtype=author&query=Han%2C+C">Chih-Chiang Han</a>, <a href="/search/astro-ph?searchtype=author&query=Hecht%2C+M+H">Michael H. Hecht</a>, <a href="/search/astro-ph?searchtype=author&query=Huang%2C+Y">Yau-De Huang</a>, <a href="/search/astro-ph?searchtype=author&query=Janssen%2C+M">Michael Janssen</a>, <a href="/search/astro-ph?searchtype=author&query=Keating%2C+G+K">Garrett K. Keating</a>, <a href="/search/astro-ph?searchtype=author&query=Koay%2C+J+Y">Jun Yi Koay</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=Lo%2C+W">Wen-Ping Lo</a>, <a href="/search/astro-ph?searchtype=author&query=Matsushita%2C+S">Satoki Matsushita</a>, <a href="/search/astro-ph?searchtype=author&query=Matthews%2C+L+D">Lynn D. Matthews</a>, <a href="/search/astro-ph?searchtype=author&query=Moran%2C+J+M">James M. Moran</a> , et al. (254 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="2410.07453v1-abstract-short" style="display: inline;"> The first very long baseline interferometry (VLBI) detections at 870$渭$m wavelength (345$\,$GHz frequency) are reported, achieving the highest diffraction-limited angular resolution yet obtained from the surface of the Earth, and the highest-frequency example of the VLBI technique to date. These include strong detections for multiple sources observed on inter-continental baselines between telescop… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.07453v1-abstract-full').style.display = 'inline'; document.getElementById('2410.07453v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.07453v1-abstract-full" style="display: none;"> The first very long baseline interferometry (VLBI) detections at 870$渭$m wavelength (345$\,$GHz frequency) are reported, achieving the highest diffraction-limited angular resolution yet obtained from the surface of the Earth, and the highest-frequency example of the VLBI technique to date. These include strong detections for multiple sources observed on inter-continental baselines between telescopes in Chile, Hawaii, and Spain, obtained during observations in October 2018. The longest-baseline detections approach 11$\,$G$位$ corresponding to an angular resolution, or fringe spacing, of 19$渭$as. The Allan deviation of the visibility phase at 870$渭$m is comparable to that at 1.3$\,$mm on the relevant integration time scales between 2 and 100$\,$s. The detections confirm that the sensitivity and signal chain stability of stations in the Event Horizon Telescope (EHT) array are suitable for VLBI observations at 870$渭$m. Operation at this short wavelength, combined with anticipated enhancements of the EHT, will lead to a unique high angular resolution instrument for black hole studies, capable of resolving the event horizons of supermassive black holes in both space and time. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.07453v1-abstract-full').style.display = 'none'; document.getElementById('2410.07453v1-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 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">Corresponding author: S. Doeleman</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> The Astronomical Journal, Volume 168, Issue 3, id.130, 19 pp. 2024 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.00097">arXiv:2405.00097</a> <span> [<a href="https://arxiv.org/pdf/2405.00097">pdf</a>, <a href="https://arxiv.org/format/2405.00097">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/10.1051/0004-6361/202450218">10.1051/0004-6361/202450218 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Evidence for a toroidal magnetic field in the core of 3C 84 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Paraschos%2C+G+F">G. F. Paraschos</a>, <a href="/search/astro-ph?searchtype=author&query=Debbrecht%2C+L+C">L. C. Debbrecht</a>, <a href="/search/astro-ph?searchtype=author&query=Kramer%2C+J+A">J. A. Kramer</a>, <a href="/search/astro-ph?searchtype=author&query=Traianou%2C+E">E. Traianou</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">I. Liodakis</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=Kim%2C+J+-">J. -Y. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Janssen%2C+M">M. Janssen</a>, <a href="/search/astro-ph?searchtype=author&query=Nair%2C+D+G">D. G. Nair</a>, <a href="/search/astro-ph?searchtype=author&query=Savolainen%2C+T">T. Savolainen</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">E. Ros</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</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=Lisakov%2C+M">M. Lisakov</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=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="2405.00097v2-abstract-short" style="display: inline;"> The spatial scales of relativistic radio jets, probed by relativistic magneto-hydrodynamic jet launching simulations (RMHDs) and by most very-long-baseline interferometry (VLBI) observations differ by an order of magnitude. Bridging the gap between these RMHD simulations and VLBI observations requires selecting nearby active galactic nuclei (AGN), the parsec-scale region of which can be resolved.… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.00097v2-abstract-full').style.display = 'inline'; document.getElementById('2405.00097v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.00097v2-abstract-full" style="display: none;"> The spatial scales of relativistic radio jets, probed by relativistic magneto-hydrodynamic jet launching simulations (RMHDs) and by most very-long-baseline interferometry (VLBI) observations differ by an order of magnitude. Bridging the gap between these RMHD simulations and VLBI observations requires selecting nearby active galactic nuclei (AGN), the parsec-scale region of which can be resolved. 3C 84 is a nearby bright AGN fulfilling the necessary requirements: it is launching a powerful, relativistic jet powered by a central supermassive black hole, while also being very bright. Using 22 GHz global VLBI measurements of 3C 84 we aim to study its sub-parsec region in both total intensity and linear polarisation, to explore the properties of this jet, with a linear resolution of $\sim0.1$ parsec. We test different simulation setups by altering the bulk Lorentz factor $螕$ of the jet, as well as the magnetic field configuration (toroidal, poloidal, helical). We confirm the persistence of a limb brightened structure, which reaches deep into the sub-parsec region. The corresponding electric vector position angles (EVPAs) follow the bulk jet flow inside but tend to be orthogonal to it near the edges. Our state-of-the-art RMHD simulations show that this geometry is consistent with a spine-sheath model, associated with a mildly relativistic flow and a toroidal magnetic field configuration. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.00097v2-abstract-full').style.display = 'none'; document.getElementById('2405.00097v2-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 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 April, 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">10 pages, 8 figures, accepted for publication in 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 686, L5 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.17623">arXiv:2404.17623</a> <span> [<a href="https://arxiv.org/pdf/2404.17623">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> </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/10.1051/0004-6361/202450497">10.1051/0004-6361/202450497 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Broadband Multi-wavelength Properties of M87 during the 2018 EHT Campaign including a Very High Energy Flaring Episode </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Algaba%2C+J+C">J. C. Algaba</a>, <a href="/search/astro-ph?searchtype=author&query=Balokovic%2C+M">M. Balokovic</a>, <a href="/search/astro-ph?searchtype=author&query=Chandra%2C+S">S. Chandra</a>, <a href="/search/astro-ph?searchtype=author&query=Cheong%2C+W+Y">W. Y. Cheong</a>, <a href="/search/astro-ph?searchtype=author&query=Cui%2C+Y+Z">Y. Z. Cui</a>, <a href="/search/astro-ph?searchtype=author&query=D%27Ammando%2C+F">F. D'Ammando</a>, <a href="/search/astro-ph?searchtype=author&query=Falcone%2C+A+D">A. D. Falcone</a>, <a href="/search/astro-ph?searchtype=author&query=Ford%2C+N+M">N. M. Ford</a>, <a href="/search/astro-ph?searchtype=author&query=Giroletti%2C+M">M. Giroletti</a>, <a href="/search/astro-ph?searchtype=author&query=Goddi%2C+C">C. Goddi</a>, <a href="/search/astro-ph?searchtype=author&query=Gurwell%2C+M+A">M. A. Gurwell</a>, <a href="/search/astro-ph?searchtype=author&query=Hada%2C+K">K. Hada</a>, <a href="/search/astro-ph?searchtype=author&query=Haggard%2C+D">D. Haggard</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S">S. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Kaur%2C+A">A. Kaur</a>, <a href="/search/astro-ph?searchtype=author&query=Kawashima%2C+T">T. Kawashima</a>, <a href="/search/astro-ph?searchtype=author&query=Kerby%2C+S">S. Kerby</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=Kino%2C+M">M. Kino</a>, <a href="/search/astro-ph?searchtype=author&query=Kravchenko%2C+E+V">E. V. Kravchenko</a>, <a href="/search/astro-ph?searchtype=author&query=Lee%2C+S+S">S. S. Lee</a>, <a href="/search/astro-ph?searchtype=author&query=Lu%2C+R+S">R. S. Lu</a>, <a href="/search/astro-ph?searchtype=author&query=Markoff%2C+S">S. Markoff</a>, <a href="/search/astro-ph?searchtype=author&query=Michail%2C+J">J. Michail</a>, <a href="/search/astro-ph?searchtype=author&query=Neilsen%2C+J">J. Neilsen</a> , et al. (721 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="2404.17623v3-abstract-short" style="display: inline;"> The nearby elliptical galaxy M87 contains one of the only two supermassive black holes whose emission surrounding the event horizon has been imaged by the Event Horizon Telescope (EHT). In 2018, more than two dozen multi-wavelength (MWL) facilities (from radio to gamma-ray energies) took part in the second M87 EHT campaign. The goal of this extensive MWL campaign was to better understand the physi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.17623v3-abstract-full').style.display = 'inline'; document.getElementById('2404.17623v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.17623v3-abstract-full" style="display: none;"> The nearby elliptical galaxy M87 contains one of the only two supermassive black holes whose emission surrounding the event horizon has been imaged by the Event Horizon Telescope (EHT). In 2018, more than two dozen multi-wavelength (MWL) facilities (from radio to gamma-ray energies) took part in the second M87 EHT campaign. The goal of this extensive MWL campaign was to better understand the physics of the accreting black hole M87*, the relationship between the inflow and inner jets, and the high-energy particle acceleration. Understanding the complex astrophysics is also a necessary first step towards performing further tests of general relativity. The MWL campaign took place in April 2018, overlapping with the EHT M87* observations. We present a new, contemporaneous spectral energy distribution (SED) ranging from radio to very high energy (VHE) gamma-rays, as well as details of the individual observations and light curves. We also conduct phenomenological modelling to investigate the basic source properties. We present the first VHE gamma-ray flare from M87 detected since 2010. The flux above 350 GeV has more than doubled within a period of about 36 hours. We find that the X-ray flux is enhanced by about a factor of two compared to 2017, while the radio and millimetre core fluxes are consistent between 2017 and 2018. We detect evidence for a monotonically increasing jet position angle that corresponds to variations in the bright spot of the EHT image. Our results show the value of continued MWL monitoring together with precision imaging for addressing the origins of high-energy particle acceleration. While we cannot currently pinpoint the precise location where such acceleration takes place, the new VHE gamma-ray flare already presents a challenge to simple one-zone leptonic emission model approaches, and emphasises the need for combined image and spectral modelling. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.17623v3-abstract-full').style.display = 'none'; document.getElementById('2404.17623v3-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 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">46 pages, 23 figures, accepted by Astronomy & Astrophysics on August. 29, 2024</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 692, A140 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.00927">arXiv:2402.00927</a> <span> [<a href="https://arxiv.org/pdf/2402.00927">pdf</a>, <a href="https://arxiv.org/format/2402.00927">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/10.1051/0004-6361/202348308">10.1051/0004-6361/202348308 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Ordered magnetic fields around the 3C 84 central black hole </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Paraschos%2C+G+F">G. F. Paraschos</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+J+-">J. -Y. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Wielgus%2C+M">M. Wielgus</a>, <a href="/search/astro-ph?searchtype=author&query=R%C3%B6der%2C+J">J. R枚der</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=Ros%2C+E">E. Ros</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">I. Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Myserlis%2C+I">I. Myserlis</a>, <a href="/search/astro-ph?searchtype=author&query=Moscibrodzka%2C+M">M. Moscibrodzka</a>, <a href="/search/astro-ph?searchtype=author&query=Traianou%2C+E">E. Traianou</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=Blackburn%2C+L">L. Blackburn</a>, <a href="/search/astro-ph?searchtype=author&query=Chan%2C+C+-">C. -K. Chan</a>, <a href="/search/astro-ph?searchtype=author&query=Issaoun%2C+S">S. Issaoun</a>, <a href="/search/astro-ph?searchtype=author&query=Janssen%2C+M">M. Janssen</a>, <a href="/search/astro-ph?searchtype=author&query=Johnson%2C+M+D">M. D. Johnson</a>, <a href="/search/astro-ph?searchtype=author&query=Fish%2C+V+L">V. L. Fish</a>, <a href="/search/astro-ph?searchtype=author&query=Akiyama%2C+K">K. Akiyama</a>, <a href="/search/astro-ph?searchtype=author&query=Alberdi%2C+A">A. Alberdi</a>, <a href="/search/astro-ph?searchtype=author&query=Alef%2C+W">W. Alef</a>, <a href="/search/astro-ph?searchtype=author&query=Algaba%2C+J+C">J. C. Algaba</a>, <a href="/search/astro-ph?searchtype=author&query=Anantua%2C+R">R. Anantua</a>, <a href="/search/astro-ph?searchtype=author&query=Asada%2C+K">K. Asada</a>, <a href="/search/astro-ph?searchtype=author&query=Azulay%2C+R">R. Azulay</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a> , et al. (258 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="2402.00927v1-abstract-short" style="display: inline;"> 3C84 is a nearby radio source with a complex total intensity structure, showing linear polarisation and spectral patterns. A detailed investigation of the central engine region necessitates the use of VLBI above the hitherto available maximum frequency of 86GHz. Using ultrahigh resolution VLBI observations at the highest available frequency of 228GHz, we aim to directly detect compact structures a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.00927v1-abstract-full').style.display = 'inline'; document.getElementById('2402.00927v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.00927v1-abstract-full" style="display: none;"> 3C84 is a nearby radio source with a complex total intensity structure, showing linear polarisation and spectral patterns. A detailed investigation of the central engine region necessitates the use of VLBI above the hitherto available maximum frequency of 86GHz. Using ultrahigh resolution VLBI observations at the highest available frequency of 228GHz, we aim to directly detect compact structures and understand the physical conditions in the compact region of 3C84. We used EHT 228GHz observations and, given the limited (u,v)-coverage, applied geometric model fitting to the data. We also employed quasi-simultaneously observed, multi-frequency VLBI data for the source in order to carry out a comprehensive analysis of the core structure. We report the detection of a highly ordered, strong magnetic field around the central, SMBH of 3C84. The brightness temperature analysis suggests that the system is in equipartition. We determined a turnover frequency of $谓_m=(113\pm4)$GHz, a corresponding synchrotron self-absorbed magnetic field of $B_{SSA}=(2.9\pm1.6)$G, and an equipartition magnetic field of $B_{eq}=(5.2\pm0.6)$G. Three components are resolved with the highest fractional polarisation detected for this object ($m_\textrm{net}=(17.0\pm3.9)$%). The positions of the components are compatible with those seen in low-frequency VLBI observations since 2017-2018. We report a steeply negative slope of the spectrum at 228GHz. We used these findings to test models of jet formation, propagation, and Faraday rotation in 3C84. The findings of our investigation into different flow geometries and black hole spins support an advection-dominated accretion flow in a magnetically arrested state around a rapidly rotating supermassive black hole as a model of the jet-launching system in the core of 3C84. However, systematic uncertainties due to the limited (u,v)-coverage, however, cannot be ignored. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.00927v1-abstract-full').style.display = 'none'; document.getElementById('2402.00927v1-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 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 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">15 pages, 6 figures, published in A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Issue: A&A Volume 682, February 2024; Article number: L3; Number of pages: 15 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.06296">arXiv:2401.06296</a> <span> [<a href="https://arxiv.org/pdf/2401.06296">pdf</a>, <a href="https://arxiv.org/format/2401.06296">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"> TELAMON: Effelsberg monitoring of AGN jets with very-high-energy astroparticle emission -- I. Program description and sample characterization </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Eppel%2C+F">F. Eppel</a>, <a href="/search/astro-ph?searchtype=author&query=Kadler%2C+M">M. Kadler</a>, <a href="/search/astro-ph?searchtype=author&query=He%C3%9Fd%C3%B6rfer%2C+J">J. He脽d枚rfer</a>, <a href="/search/astro-ph?searchtype=author&query=Benke%2C+P">P. Benke</a>, <a href="/search/astro-ph?searchtype=author&query=Debbrecht%2C+L">L. Debbrecht</a>, <a href="/search/astro-ph?searchtype=author&query=Eich%2C+J">J. Eich</a>, <a href="/search/astro-ph?searchtype=author&query=Gokus%2C+A">A. Gokus</a>, <a href="/search/astro-ph?searchtype=author&query=H%C3%A4mmerich%2C+S">S. H盲mmerich</a>, <a href="/search/astro-ph?searchtype=author&query=Kirchner%2C+D">D. Kirchner</a>, <a href="/search/astro-ph?searchtype=author&query=Paraschos%2C+G+F">G. F. Paraschos</a>, <a href="/search/astro-ph?searchtype=author&query=R%C3%B6sch%2C+F">F. R枚sch</a>, <a href="/search/astro-ph?searchtype=author&query=Schulga%2C+W">W. Schulga</a>, <a href="/search/astro-ph?searchtype=author&query=Sinapius%2C+J">J. Sinapius</a>, <a href="/search/astro-ph?searchtype=author&query=Weber%2C+P">P. Weber</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Dorner%2C+D">D. Dorner</a>, <a href="/search/astro-ph?searchtype=author&query=Edwards%2C+P+G">P. G. Edwards</a>, <a href="/search/astro-ph?searchtype=author&query=Giroletti%2C+M">M. Giroletti</a>, <a href="/search/astro-ph?searchtype=author&query=Kraus%2C+A">A. Kraus</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">O. Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=Koyama%2C+S">S. Koyama</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=Mannheim%2C+K">K. Mannheim</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">E. Ros</a>, <a href="/search/astro-ph?searchtype=author&query=Zacharias%2C+M">M. Zacharias</a> , et al. (1 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="2401.06296v1-abstract-short" style="display: inline;"> Aims. We introduce the TELAMON program which is using the Effelsberg 100-m telescope to monitor the radio spectra of active galactic nuclei (AGN) under scrutiny in astroparticle physics, specifically TeV blazars and candidate neutrino-associated AGN. Here, we present and characterize our main sample of TeV-detected blazars. Methods. We analyze the data sample from the first ~2.5 years of observa… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.06296v1-abstract-full').style.display = 'inline'; document.getElementById('2401.06296v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.06296v1-abstract-full" style="display: none;"> Aims. We introduce the TELAMON program which is using the Effelsberg 100-m telescope to monitor the radio spectra of active galactic nuclei (AGN) under scrutiny in astroparticle physics, specifically TeV blazars and candidate neutrino-associated AGN. Here, we present and characterize our main sample of TeV-detected blazars. Methods. We analyze the data sample from the first ~2.5 years of observations between August 2020 and February 2023 in the range from 14 GHz to 45 GHz. During this pilot phase, we have observed all 59 TeV-detected blazars in the Northern Hemisphere (i.e., Dec. >0掳) known at the time of observation. We discuss the basic data reduction and calibration procedures used for all TELAMON data and introduce a sub-band averaging method used to calculate average light curves for the sources in our sample. Results. The TeV-selected sources in our sample exhibit a median flux density of 0.12 Jy at 20 mm, 0.20 Jy at 14 mm and 0.60 Jy at 7 mm. The spectrum for most of the sources is consistent with a flat radio spectrum and we find a median spectral index ($S(谓)\propto谓^伪$) of $伪=-0.11$. Our results on flux density and spectral index are consistent with previous studies of TeV-selected blazars. Compared to the GeV-selected F-GAMMA sample, TELAMON sources are significantly fainter in the radio band. This is consistent with the double-humped spectrum of blazars being shifted towards higher frequencies for TeV-emitters (in particular for high-synchrotron peaked BL Lac type objects), which results in a lower radio flux density. The spectral index distribution of our TeV-selected blazar sample is not significantly different from the GeV-selected F-GAMMA sample. Moreover, we present a strategy to track the light curve evolution of sources in our sample for future variability and correlation analysis. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.06296v1-abstract-full').style.display = 'none'; document.getElementById('2401.06296v1-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 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, 11 figures, 4 tables, 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/2312.14490">arXiv:2312.14490</a> <span> [<a href="https://arxiv.org/pdf/2312.14490">pdf</a>, <a href="https://arxiv.org/format/2312.14490">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"> Milliarcsecond Localisation of the Hyperactive Repeating FRB 20220912A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Hewitt%2C+D+M">Dant茅 M. Hewitt</a>, <a href="/search/astro-ph?searchtype=author&query=Bhandari%2C+S">Shivani Bhandari</a>, <a href="/search/astro-ph?searchtype=author&query=Marcote%2C+B">Benito Marcote</a>, <a href="/search/astro-ph?searchtype=author&query=Hessels%2C+J+W+T">Jason W. T. Hessels</a>, <a href="/search/astro-ph?searchtype=author&query=Nimmo%2C+K">Kenzie Nimmo</a>, <a href="/search/astro-ph?searchtype=author&query=Kirsten%2C+F">Franz Kirsten</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">Uwe Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Bezrukovs%2C+V">Vladislavs Bezrukovs</a>, <a href="/search/astro-ph?searchtype=author&query=Bhardwaj%2C+M">Mohit Bhardwaj</a>, <a href="/search/astro-ph?searchtype=author&query=Blaauw%2C+R">Richard Blaauw</a>, <a href="/search/astro-ph?searchtype=author&query=Bray%2C+J+D">Justin D. Bray</a>, <a href="/search/astro-ph?searchtype=author&query=Buttaccio%2C+S">Salvatore Buttaccio</a>, <a href="/search/astro-ph?searchtype=author&query=Corongiu%2C+A">Alessandro Corongiu</a>, <a href="/search/astro-ph?searchtype=author&query=Gawro%C5%84ski%2C+M+P">Marcin P. Gawro艅ski</a>, <a href="/search/astro-ph?searchtype=author&query=Giroletti%2C+M">Marcello Giroletti</a>, <a href="/search/astro-ph?searchtype=author&query=Keimpema%2C+A">Aard Keimpema</a>, <a href="/search/astro-ph?searchtype=author&query=Maccaferri%2C+G+M">Giuseppe M. Maccaferri</a>, <a href="/search/astro-ph?searchtype=author&query=Paragi%2C+Z">Zsolt Paragi</a>, <a href="/search/astro-ph?searchtype=author&query=Trudu%2C+M">Matteo Trudu</a>, <a href="/search/astro-ph?searchtype=author&query=Snelders%2C+M+P">Mark P. Snelders</a>, <a href="/search/astro-ph?searchtype=author&query=Venturi%2C+T">Tiziana Venturi</a>, <a href="/search/astro-ph?searchtype=author&query=Wang%2C+N">Na Wang</a>, <a href="/search/astro-ph?searchtype=author&query=Williams-Baldwin%2C+D+R+A">David R. A. Williams-Baldwin</a>, <a href="/search/astro-ph?searchtype=author&query=Wrigley%2C+N+H">Nicholas H. Wrigley</a>, <a href="/search/astro-ph?searchtype=author&query=Yang%2C+J">Jun Yang</a> , et al. (1 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="2312.14490v1-abstract-short" style="display: inline;"> We present very-long-baseline interferometry (VLBI) observations of the hyperactive repeating FRB 20220912A using the European VLBI Network (EVN) with an EVN-Lite setup. We detected 150 bursts from FRB 20220912A over two observing epochs in October 2022. Combining the data of these bursts allows us to localise FRB 20220912A to a precision of a few milliarcseconds, corresponding to a transverse sca… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.14490v1-abstract-full').style.display = 'inline'; document.getElementById('2312.14490v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.14490v1-abstract-full" style="display: none;"> We present very-long-baseline interferometry (VLBI) observations of the hyperactive repeating FRB 20220912A using the European VLBI Network (EVN) with an EVN-Lite setup. We detected 150 bursts from FRB 20220912A over two observing epochs in October 2022. Combining the data of these bursts allows us to localise FRB 20220912A to a precision of a few milliarcseconds, corresponding to a transverse scale of less than 10 pc at the distance of the source. The precision of this localisation shows that FRB 20220912A lies closer to the centre of its host galaxy than previously found, although still significantly offset from the host galaxy's nucleus. On arcsecond scales, FRB 20220912A is coincident with a persistent continuum radio source known from archival observations, however, we find no compact persistent emission on milliarcsecond scales. The persistent radio emission is thus likely to be from star-formation in the host galaxy. This is in contrast to some other active FRBs, such as FRB 20121102A and FRB 20190520B. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.14490v1-abstract-full').style.display = 'none'; document.getElementById('2312.14490v1-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 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">13 pages, 7 figures, submitted to MNRAS, comments most welcome</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2309.14794">arXiv:2309.14794</a> <span> [<a href="https://arxiv.org/pdf/2309.14794">pdf</a>, <a href="https://arxiv.org/format/2309.14794">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"> TELAMON: Effelsberg Monitoring of AGN Jets with Very-High-Energy Astroparticle Emissions -- Polarization properties </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=He%C3%9Fd%C3%B6rfer%2C+J">J. He脽d枚rfer</a>, <a href="/search/astro-ph?searchtype=author&query=Kadler%2C+M">M. Kadler</a>, <a href="/search/astro-ph?searchtype=author&query=Benke%2C+P">P. Benke</a>, <a href="/search/astro-ph?searchtype=author&query=Debbrecht%2C+L">L. Debbrecht</a>, <a href="/search/astro-ph?searchtype=author&query=Eich%2C+J">J. Eich</a>, <a href="/search/astro-ph?searchtype=author&query=Eppel%2C+F">F. Eppel</a>, <a href="/search/astro-ph?searchtype=author&query=Gokus%2C+A">A. Gokus</a>, <a href="/search/astro-ph?searchtype=author&query=H%C3%A4mmerich%2C+S">S. H盲mmerich</a>, <a href="/search/astro-ph?searchtype=author&query=Kirchner%2C+D">D. Kirchner</a>, <a href="/search/astro-ph?searchtype=author&query=Paraschos%2C+G+F">G. F. Paraschos</a>, <a href="/search/astro-ph?searchtype=author&query=R%C3%B6sch%2C+F">F. R枚sch</a>, <a href="/search/astro-ph?searchtype=author&query=Schulga%2C+W">W. Schulga</a>, <a href="/search/astro-ph?searchtype=author&query=Sinapius%2C+J">J. Sinapius</a>, <a href="/search/astro-ph?searchtype=author&query=Weber%2C+P">P. Weber</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/astro-ph?searchtype=author&query=Buson%2C+S">S. Buson</a>, <a href="/search/astro-ph?searchtype=author&query=Dorner%2C+D">D. Dorner</a>, <a href="/search/astro-ph?searchtype=author&query=Edwards%2C+P+G">P. G. Edwards</a>, <a href="/search/astro-ph?searchtype=author&query=Fromm%2C+C+M">C. M. Fromm</a>, <a href="/search/astro-ph?searchtype=author&query=Giroletti%2C+M">M. Giroletti</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">O. Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=Kappes%2C+A">A. Kappes</a>, <a href="/search/astro-ph?searchtype=author&query=Koyama%2C+S">S. Koyama</a>, <a href="/search/astro-ph?searchtype=author&query=Kraus%2C+A">A. Kraus</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="2309.14794v2-abstract-short" style="display: inline;"> We present recent results of the TELAMON program, which is using the Effelsberg 100-m telescope to monitor the radio spectra of active galactic nuclei (AGN) under scrutiny in astroparticle physics, namely TeV blazars and neutrino-associated AGN. Our sample includes all known Northern TeV-emitting blazars as well as blazars positionally coincident with IceCube neutrino alerts. Polarization can give… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.14794v2-abstract-full').style.display = 'inline'; document.getElementById('2309.14794v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.14794v2-abstract-full" style="display: none;"> We present recent results of the TELAMON program, which is using the Effelsberg 100-m telescope to monitor the radio spectra of active galactic nuclei (AGN) under scrutiny in astroparticle physics, namely TeV blazars and neutrino-associated AGN. Our sample includes all known Northern TeV-emitting blazars as well as blazars positionally coincident with IceCube neutrino alerts. Polarization can give additional insight into the source properties, as the polarized emission is often found to vary on different timescales and amplitudes than the total intensity emission. Here, we present an overview of the polarization properties of the TeV-emitting TELAMON sources at four frequencies in the 20 mm and 7 mm bands. While at 7 mm roughly $82\,\%$ of all observed sources are found to be significantly polarized, for 20 mm the percentage is $\sim58\,\%$. We find that most of the sources exhibit mean fractional polarizations of $<5\%$, matching the expectations of rather low polarization levels in these sources from previous studies at lower radio frequencies. Nevertheless, we demonstrate examples of how the polarized emission can provide additional information over the total intensity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.14794v2-abstract-full').style.display = 'none'; document.getElementById('2309.14794v2-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 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 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">9 pages, 2 figures, Proceedings of the 38th International Cosmic Ray Conference (ICRC2023)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.15381">arXiv:2308.15381</a> <span> [<a href="https://arxiv.org/pdf/2308.15381">pdf</a>, <a href="https://arxiv.org/format/2308.15381">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="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> </div> <p class="title is-5 mathjax"> A search for pulsars around Sgr A* in the first Event Horizon Telescope dataset </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Torne%2C+P">Pablo Torne</a>, <a href="/search/astro-ph?searchtype=author&query=Liu%2C+K">Kuo Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Eatough%2C+R+P">Ralph P. Eatough</a>, <a href="/search/astro-ph?searchtype=author&query=Wongphechauxsorn%2C+J">Jompoj Wongphechauxsorn</a>, <a href="/search/astro-ph?searchtype=author&query=Cordes%2C+J+M">James M. Cordes</a>, <a href="/search/astro-ph?searchtype=author&query=Desvignes%2C+G">Gregory Desvignes</a>, <a href="/search/astro-ph?searchtype=author&query=De+Laurentis%2C+M">Mariafelicia De Laurentis</a>, <a href="/search/astro-ph?searchtype=author&query=Kramer%2C+M">Michael Kramer</a>, <a href="/search/astro-ph?searchtype=author&query=Ransom%2C+S+M">Scott M. Ransom</a>, <a href="/search/astro-ph?searchtype=author&query=Chatterjee%2C+S">Shami Chatterjee</a>, <a href="/search/astro-ph?searchtype=author&query=Wharton%2C+R">Robert Wharton</a>, <a href="/search/astro-ph?searchtype=author&query=Karuppusamy%2C+R">Ramesh Karuppusamy</a>, <a href="/search/astro-ph?searchtype=author&query=Blackburn%2C+L">Lindy Blackburn</a>, <a href="/search/astro-ph?searchtype=author&query=Janssen%2C+M">Michael Janssen</a>, <a href="/search/astro-ph?searchtype=author&query=Chan%2C+C">Chi-kwan Chan</a>, <a href="/search/astro-ph?searchtype=author&query=Crew%2C+G+B">Geoffrey B. Crew</a>, <a href="/search/astro-ph?searchtype=author&query=Matthews%2C+L+D">Lynn D. Matthews</a>, <a href="/search/astro-ph?searchtype=author&query=Goddi%2C+C">Ciriaco Goddi</a>, <a href="/search/astro-ph?searchtype=author&query=Rottmann%2C+H">Helge Rottmann</a>, <a href="/search/astro-ph?searchtype=author&query=Wagner%2C+J">Jan Wagner</a>, <a href="/search/astro-ph?searchtype=author&query=Sanchez%2C+S">Salvador Sanchez</a>, <a href="/search/astro-ph?searchtype=author&query=Ruiz%2C+I">Ignacio Ruiz</a>, <a href="/search/astro-ph?searchtype=author&query=Abbate%2C+F">Federico Abbate</a>, <a href="/search/astro-ph?searchtype=author&query=Bower%2C+G+C">Geoffrey C. Bower</a>, <a href="/search/astro-ph?searchtype=author&query=Salamanca%2C+J+J">Juan J. Salamanca</a> , et al. (261 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="2308.15381v1-abstract-short" style="display: inline;"> The Event Horizon Telescope (EHT) observed in 2017 the supermassive black hole at the center of the Milky Way, Sagittarius A* (Sgr A*), at a frequency of 228.1 GHz ($位$=1.3 mm). The fundamental physics tests that even a single pulsar orbiting Sgr A* would enable motivate searching for pulsars in EHT datasets. The high observing frequency means that pulsars - which typically exhibit steep emission… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.15381v1-abstract-full').style.display = 'inline'; document.getElementById('2308.15381v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.15381v1-abstract-full" style="display: none;"> The Event Horizon Telescope (EHT) observed in 2017 the supermassive black hole at the center of the Milky Way, Sagittarius A* (Sgr A*), at a frequency of 228.1 GHz ($位$=1.3 mm). The fundamental physics tests that even a single pulsar orbiting Sgr A* would enable motivate searching for pulsars in EHT datasets. The high observing frequency means that pulsars - which typically exhibit steep emission spectra - are expected to be very faint. However, it also negates pulse scattering, an effect that could hinder pulsar detections in the Galactic Center. Additionally, magnetars or a secondary inverse Compton emission could be stronger at millimeter wavelengths than at lower frequencies. We present a search for pulsars close to Sgr A* using the data from the three most-sensitive stations in the EHT 2017 campaign: the Atacama Large Millimeter/submillimeter Array, the Large Millimeter Telescope and the IRAM 30 m Telescope. We apply three detection methods based on Fourier-domain analysis, the Fast-Folding-Algorithm and single pulse search targeting both pulsars and burst-like transient emission; using the simultaneity of the observations to confirm potential candidates. No new pulsars or significant bursts were found. Being the first pulsar search ever carried out at such high radio frequencies, we detail our analysis methods and give a detailed estimation of the sensitivity of the search. We conclude that the EHT 2017 observations are only sensitive to a small fraction ($\lesssim$2.2%) of the pulsars that may exist close to Sgr A*, motivating further searches for fainter pulsars in the region. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.15381v1-abstract-full').style.display = 'none'; document.getElementById('2308.15381v1-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 August, 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">33 pages, 7 figures, 6 Tables. 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/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/2304.09816">arXiv:2304.09816</a> <span> [<a href="https://arxiv.org/pdf/2304.09816">pdf</a>, <a href="https://arxiv.org/format/2304.09816">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/accf17">10.3847/1538-4357/accf17 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> RadioAstron Space VLBI Imaging of the jet in M87: I. Detection of high brightness temperature at 22 GHz </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kim%2C+J">Jae-Young Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Savolainen%2C+T">Tuomas Savolainen</a>, <a href="/search/astro-ph?searchtype=author&query=Voitsik%2C+P">Petr Voitsik</a>, <a href="/search/astro-ph?searchtype=author&query=Kravchenko%2C+E+V">Evgeniya V. Kravchenko</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=Kovalev%2C+Y+Y">Yuri Y. Kovalev</a>, <a href="/search/astro-ph?searchtype=author&query=M%C3%BCller%2C+H">Hendrik M眉ller</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=Sokolovsky%2C+K+V">Kirill V. Sokolovsky</a>, <a href="/search/astro-ph?searchtype=author&query=Bruni%2C+G">Gabriele Bruni</a>, <a href="/search/astro-ph?searchtype=author&query=Edwards%2C+P+G">Philip G. Edwards</a>, <a href="/search/astro-ph?searchtype=author&query=Reynolds%2C+C">Cormac Reynolds</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">Uwe Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Gurvits%2C+L+I">Leonid I. Gurvits</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=Hada%2C+K">Kazuhiro Hada</a>, <a href="/search/astro-ph?searchtype=author&query=Giroletti%2C+M">Marcello Giroletti</a>, <a href="/search/astro-ph?searchtype=author&query=Orienti%2C+M">Monica Orienti</a>, <a href="/search/astro-ph?searchtype=author&query=Anderson%2C+J+M">James M. Anderson</a>, <a href="/search/astro-ph?searchtype=author&query=Lee%2C+S">Sang-Sung Lee</a>, <a href="/search/astro-ph?searchtype=author&query=Sohn%2C+B+W">Bong Won Sohn</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="2304.09816v1-abstract-short" style="display: inline;"> We present results from the first 22 GHz space very-long-baseline interferometric (VLBI) imaging observations of M87 by RadioAstron. As a part of the Nearby AGN Key Science Program, the source was observed in Feb 2014 at 22 GHz with 21 ground stations, reaching projected $(u,v)$-spacings up to $\sim11\,$G$位$. The imaging experiment was complemented by snapshot RadioAstron data of M87 obtained duri… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.09816v1-abstract-full').style.display = 'inline'; document.getElementById('2304.09816v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.09816v1-abstract-full" style="display: none;"> We present results from the first 22 GHz space very-long-baseline interferometric (VLBI) imaging observations of M87 by RadioAstron. As a part of the Nearby AGN Key Science Program, the source was observed in Feb 2014 at 22 GHz with 21 ground stations, reaching projected $(u,v)$-spacings up to $\sim11\,$G$位$. The imaging experiment was complemented by snapshot RadioAstron data of M87 obtained during 2013--2016 from the AGN Survey Key Science Program. Their longest baselines extend up to $\sim25\,$G$位$. For all these measurements, fringes are detected only up to $\sim$2.8 Earth Diameter or $\sim$3 G$位$ baseline lengths, resulting in a new image with angular resolution of $\sim150\,渭$as or $\sim20$ Schwarzschild radii spatial resolution. The new image not only shows edge-brightened jet and counterjet structures down to submilliarcsecond scales but also clearly resolves the VLBI core region. While the overall size of the core is comparable to those reported in the literature, the ground-space fringe detection and slightly super-resolved RadioAstron image suggest the presence of substructures in the nucleus, whose minimum brightness temperature exceeds $T_{\rm B, min}\sim10^{12}\,$K. It is challenging to explain the origin of this record-high $T_{\rm B, min}$ value for M87 by pure Doppler boosting effect with a simple conical jet geometry and known jet speed. Therefore, this can be evidence for more extreme Doppler boosting due to a blazar-like small jet viewing angle or highly efficient particle acceleration processes occurring already at the base of the outflow. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.09816v1-abstract-full').style.display = 'none'; document.getElementById('2304.09816v1-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 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">27 pages, 13 figures, accepted for publication in ApJ</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJ 952 (2023) 34 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.12004">arXiv:2303.12004</a> <span> [<a href="https://arxiv.org/pdf/2303.12004">pdf</a>, <a href="https://arxiv.org/format/2303.12004">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/acc586">10.3847/1538-4357/acc586 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Comparison of Polarized Radiative Transfer Codes used by the EHT Collaboration </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Prather%2C+B+S">Ben S. Prather</a>, <a href="/search/astro-ph?searchtype=author&query=Dexter%2C+J">Jason Dexter</a>, <a href="/search/astro-ph?searchtype=author&query=Moscibrodzka%2C+M">Monika Moscibrodzka</a>, <a href="/search/astro-ph?searchtype=author&query=Pu%2C+H">Hung-Yi Pu</a>, <a href="/search/astro-ph?searchtype=author&query=Bronzwaer%2C+T">Thomas Bronzwaer</a>, <a href="/search/astro-ph?searchtype=author&query=Davelaar%2C+J">Jordy Davelaar</a>, <a href="/search/astro-ph?searchtype=author&query=Younsi%2C+Z">Ziri Younsi</a>, <a href="/search/astro-ph?searchtype=author&query=Gammie%2C+C+F">Charles F. Gammie</a>, <a href="/search/astro-ph?searchtype=author&query=Gold%2C+R">Roman Gold</a>, <a href="/search/astro-ph?searchtype=author&query=Wong%2C+G+N">George N. Wong</a>, <a href="/search/astro-ph?searchtype=author&query=Akiyama%2C+K">Kazunori Akiyama</a>, <a href="/search/astro-ph?searchtype=author&query=Alberdi%2C+A">Antxon Alberdi</a>, <a href="/search/astro-ph?searchtype=author&query=Alef%2C+W">Walter Alef</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=Anantua%2C+R">Richard Anantua</a>, <a href="/search/astro-ph?searchtype=author&query=Asada%2C+K">Keiichi Asada</a>, <a href="/search/astro-ph?searchtype=author&query=Azulay%2C+R">Rebecca Azulay</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">Uwe Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Baczko%2C+A">Anne-Kathrin Baczko</a>, <a href="/search/astro-ph?searchtype=author&query=Ball%2C+D">David Ball</a>, <a href="/search/astro-ph?searchtype=author&query=Balokovi%C4%87%2C+M">Mislav Balokovi膰</a>, <a href="/search/astro-ph?searchtype=author&query=Barrett%2C+J">John Barrett</a>, <a href="/search/astro-ph?searchtype=author&query=Baub%C3%B6ck%2C+M">Michi Baub枚ck</a>, <a href="/search/astro-ph?searchtype=author&query=Benson%2C+B+A">Bradford A. Benson</a>, <a href="/search/astro-ph?searchtype=author&query=Bintley%2C+D">Dan Bintley</a> , et al. (248 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="2303.12004v1-abstract-short" style="display: inline;"> Interpretation of resolved polarized images of black holes by the Event Horizon Telescope (EHT) requires predictions of the polarized emission observable by an Earth-based instrument for a particular model of the black hole accretion system. Such predictions are generated by general relativistic radiative transfer (GRRT) codes, which integrate the equations of polarized radiative transfer in curve… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.12004v1-abstract-full').style.display = 'inline'; document.getElementById('2303.12004v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.12004v1-abstract-full" style="display: none;"> Interpretation of resolved polarized images of black holes by the Event Horizon Telescope (EHT) requires predictions of the polarized emission observable by an Earth-based instrument for a particular model of the black hole accretion system. Such predictions are generated by general relativistic radiative transfer (GRRT) codes, which integrate the equations of polarized radiative transfer in curved spacetime. A selection of ray-tracing GRRT codes used within the EHT collaboration is evaluated for accuracy and consistency in producing a selection of test images, demonstrating that the various methods and implementations of radiative transfer calculations are highly consistent. When imaging an analytic accretion model, we find that all codes produce images similar within a pixel-wise normalized mean squared error (NMSE) of 0.012 in the worst case. When imaging a snapshot from a cell-based magnetohydrodynamic simulation, we find all test images to be similar within NMSEs of 0.02, 0.04, 0.04, and 0.12 in Stokes I, Q, U , and V respectively. We additionally find the values of several image metrics relevant to published EHT results to be in agreement to much better precision than measurement uncertainties. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.12004v1-abstract-full').style.display = 'none'; document.getElementById('2303.12004v1-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 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 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 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/2302.11486">arXiv:2302.11486</a> <span> [<a href="https://arxiv.org/pdf/2302.11486">pdf</a>, <a href="https://arxiv.org/format/2302.11486">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/acaf71">10.3847/1538-4357/acaf71 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> MOMO VI: Multifrequency radio variability of the blazar OJ 287 from 2015-2022, absence of predicted 2021 precursor-flare activity, and a new binary interpretation of the 2016/2017 outburst </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Komossa%2C+S">S. Komossa</a>, <a href="/search/astro-ph?searchtype=author&query=Kraus%2C+A">A. Kraus</a>, <a href="/search/astro-ph?searchtype=author&query=Grupe%2C+D">D. Grupe</a>, <a href="/search/astro-ph?searchtype=author&query=Gonzalez%2C+A+G">A. G. Gonzalez</a>, <a href="/search/astro-ph?searchtype=author&query=Gurwell%2C+M+A">M. A. Gurwell</a>, <a href="/search/astro-ph?searchtype=author&query=Gallo%2C+L+C">L. C. Gallo</a>, <a href="/search/astro-ph?searchtype=author&query=Liu%2C+F+K">F. K. Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Myserlis%2C+I">I. Myserlis</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=Laine%2C+S">S. Laine</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</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=Parker%2C+M+L">M. L. Parker</a>, <a href="/search/astro-ph?searchtype=author&query=Yao%2C+S">S. Yao</a>, <a href="/search/astro-ph?searchtype=author&query=Berton%2C+M">M. Berton</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="2302.11486v1-abstract-short" style="display: inline;"> Based on our dedicated Swift monitoring program, MOMO, OJ 287 is one of the best-monitored blazars in the X-ray--UV--optical regime. Here, we report results from our accompanying, dense, multi-frequency (1.4--44 GHz) radio monitoring of OJ 287 between 2015 and 2022 covering a broad range of activity states. Fermi gamma-ray observations are added. We characterize the radio flux and spectral variabi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.11486v1-abstract-full').style.display = 'inline'; document.getElementById('2302.11486v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.11486v1-abstract-full" style="display: none;"> Based on our dedicated Swift monitoring program, MOMO, OJ 287 is one of the best-monitored blazars in the X-ray--UV--optical regime. Here, we report results from our accompanying, dense, multi-frequency (1.4--44 GHz) radio monitoring of OJ 287 between 2015 and 2022 covering a broad range of activity states. Fermi gamma-ray observations are added. We characterize the radio flux and spectral variability in detail, including DCF and other variability analyses, and discuss its connection with the multiwavelength emission. Deep fades of radio and optical--UV fluxes are found to occur every 1--2 years. Further, it is shown that a precursor flare of thermal bremsstrahlung predicted by one of the binary supermassive black hole (SMBH) models of OJ 287 was absent. We then focus on the nature of the extraordinary, nonthermal 2016/2017 outburst that we initially discovered with Swift. We interpret it as the latest of the famous optical double-peaked outbursts of OJ 287, favoring binary scenarios that do not require a highly precessing secondary SMBH. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.11486v1-abstract-full').style.display = 'none'; document.getElementById('2302.11486v1-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, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 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">ApJ, in press. The full radio-data tables will be available in the online material of the journal. Note that in a follow-up publication (MNRAS Letters, in press), the black hole mass of OJ 287 will be revised</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2206.03759">arXiv:2206.03759</a> <span> [<a href="https://arxiv.org/pdf/2206.03759">pdf</a>, <a href="https://arxiv.org/format/2206.03759">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/stad269">10.1093/mnras/stad269 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A burst storm from the repeating FRB 20200120E in an M81 globular cluster </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Nimmo%2C+K">K. Nimmo</a>, <a href="/search/astro-ph?searchtype=author&query=Hessels%2C+J+W+T">J. W. T. Hessels</a>, <a href="/search/astro-ph?searchtype=author&query=Snelders%2C+M+P">M. P. Snelders</a>, <a href="/search/astro-ph?searchtype=author&query=Karuppusamy%2C+R">R. Karuppusamy</a>, <a href="/search/astro-ph?searchtype=author&query=Hewitt%2C+D+M">D. M. Hewitt</a>, <a href="/search/astro-ph?searchtype=author&query=Kirsten%2C+F">F. Kirsten</a>, <a href="/search/astro-ph?searchtype=author&query=Marcote%2C+B">B. Marcote</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Bansod%2C+A">A. Bansod</a>, <a href="/search/astro-ph?searchtype=author&query=Barr%2C+E+D">E. D. Barr</a>, <a href="/search/astro-ph?searchtype=author&query=Behrend%2C+J">J. Behrend</a>, <a href="/search/astro-ph?searchtype=author&query=Bezrukovs%2C+V">V. Bezrukovs</a>, <a href="/search/astro-ph?searchtype=author&query=Buttaccio%2C+S">S. Buttaccio</a>, <a href="/search/astro-ph?searchtype=author&query=Feiler%2C+R">R. Feiler</a>, <a href="/search/astro-ph?searchtype=author&query=Gawro%C5%84ski%2C+M+P">M. P. Gawro艅ski</a>, <a href="/search/astro-ph?searchtype=author&query=Lindqvist%2C+M">M. Lindqvist</a>, <a href="/search/astro-ph?searchtype=author&query=Orbidans%2C+A">A. Orbidans</a>, <a href="/search/astro-ph?searchtype=author&query=Puchalska%2C+W">W. Puchalska</a>, <a href="/search/astro-ph?searchtype=author&query=Wang%2C+N">N. Wang</a>, <a href="/search/astro-ph?searchtype=author&query=Winchen%2C+T">T. Winchen</a>, <a href="/search/astro-ph?searchtype=author&query=Wolak%2C+P">P. Wolak</a>, <a href="/search/astro-ph?searchtype=author&query=Wu%2C+J">J. Wu</a>, <a href="/search/astro-ph?searchtype=author&query=Yuan%2C+J">J. Yuan</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="2206.03759v2-abstract-short" style="display: inline;"> The repeating fast radio burst (FRB) source FRB 20200120E is exceptional because of its proximity and association with a globular cluster. Here we report $60$ bursts detected with the Effelsberg telescope at 1.4 GHz. We observe large variations in the burst rate, and report the first FRB 20200120E `burst storm', where the source suddenly became active and 53 bursts (fluence $\geq 0.04$ Jy ms) occu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.03759v2-abstract-full').style.display = 'inline'; document.getElementById('2206.03759v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.03759v2-abstract-full" style="display: none;"> The repeating fast radio burst (FRB) source FRB 20200120E is exceptional because of its proximity and association with a globular cluster. Here we report $60$ bursts detected with the Effelsberg telescope at 1.4 GHz. We observe large variations in the burst rate, and report the first FRB 20200120E `burst storm', where the source suddenly became active and 53 bursts (fluence $\geq 0.04$ Jy ms) occurred within only 40 minutes. We find no strict periodicity in the burst arrival times, nor any evidence for periodicity in the source's activity between observations. The burst storm shows a steep energy distribution (power-law index $伪= 2.39\pm0.12$) and a bi-modal wait-time distribution, with log-normal means of 0.94$^{+0.07}_{-0.06}$ s and 23.61$^{+3.06}_{-2.71}$ s. We attribute these wait-time distribution peaks to a characteristic event timescale and pseudo-Poisson burst rate, respectively. The secondary wait-time peak at $\sim1$ s is $\sim50\times$ longer than the $\sim24$ ms timescale seen for both FRB 20121102A and FRB 20201124A -- potentially indicating a larger emission region, or slower burst propagation. FRB 20200120E shows order-of-magnitude lower burst durations and luminosities compared with FRB 20121102A and FRB 20201124A. Lastly, in contrast to FRB 20121102A, which has observed dispersion measure (DM) variations of $螖{\rm DM} >1$ pc cm$^{-3}$ on month-to-year timescales, we determine that FRB 20200120E's DM has remained stable ($螖{\rm DM} <0.15$ pc cm$^{-3}$) over $>10$ months. Overall, the observational characteristics of FRB 20200120E deviate quantitatively from other active repeaters, but it is unclear whether it is qualitatively a different type of source. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.03759v2-abstract-full').style.display = 'none'; document.getElementById('2206.03759v2-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> 23 January, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 June, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 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">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/2204.10244">arXiv:2204.10244</a> <span> [<a href="https://arxiv.org/pdf/2204.10244">pdf</a>, <a href="https://arxiv.org/format/2204.10244">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/stac792">10.1093/mnras/stac792 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> MOMO V. Effelsberg, Swift and Fermi study of the blazar and supermassive binary black hole candidate OJ 287 in a period of high activity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Komossa%2C+S">S. Komossa</a>, <a href="/search/astro-ph?searchtype=author&query=Grupe%2C+D">D. Grupe</a>, <a href="/search/astro-ph?searchtype=author&query=Kraus%2C+A">A. Kraus</a>, <a href="/search/astro-ph?searchtype=author&query=Gonzalez%2C+A">A. Gonzalez</a>, <a href="/search/astro-ph?searchtype=author&query=Gallo%2C+L+C">L. C. Gallo</a>, <a href="/search/astro-ph?searchtype=author&query=Valtonen%2C+M+J">M. J. Valtonen</a>, <a href="/search/astro-ph?searchtype=author&query=Laine%2C+S">S. Laine</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=Gurwell%2C+M+A">M. A. Gurwell</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=Ciprini%2C+S">S. Ciprini</a>, <a href="/search/astro-ph?searchtype=author&query=Myserlis%2C+I">I. Myserlis</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</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="2204.10244v1-abstract-short" style="display: inline;"> We report results from our ongoing project MOMO (Multiwavelength Observations and Modelling of OJ 287). In this latest publication of a sequence, we combine our Swift UVOT--XRT and Effelsberg radio data (2.6-44 GHz) between 2019 and 2022.04 with public SMA data and gamma-ray data from the Fermi satellite. The observational epoch covers OJ 287 in a high state of activity from radio to X-rays. The e… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.10244v1-abstract-full').style.display = 'inline'; document.getElementById('2204.10244v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.10244v1-abstract-full" style="display: none;"> We report results from our ongoing project MOMO (Multiwavelength Observations and Modelling of OJ 287). In this latest publication of a sequence, we combine our Swift UVOT--XRT and Effelsberg radio data (2.6-44 GHz) between 2019 and 2022.04 with public SMA data and gamma-ray data from the Fermi satellite. The observational epoch covers OJ 287 in a high state of activity from radio to X-rays. The epoch also covers two major events predicted by the binary supermassive black hole (SMBH) model of OJ 287. Spectral and timing analyses clearly establish: a new UV-optical minimum state in 2021 December at an epoch where the secondary SMBH is predicted to cross the disk surrounding the primary SMBH; an overall low level of gamma-ray activity in comparison to pre-2017 epochs; the presence of a remarkable, long-lasting UV--optical flare event of intermediate amplitude in 2020--2021; a high level of activity in the radio band with multiple flares; and particularly a bright, ongoing radio flare peaking in 2021 November that may be associated with a gamma-ray flare, the strongest in 6 years. Several explanations for the UV--optical minimum state are explored, including the possibility that a secondary SMBH launches a temporary jet, but the observations are best explained by variability associated with the main jet. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.10244v1-abstract-full').style.display = 'none'; document.getElementById('2204.10244v1-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 April, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">16 pages, 11 figures. Published in MNRAS (submitted in January, accepted in March)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2112.12233">arXiv:2112.12233</a> <span> [<a href="https://arxiv.org/pdf/2112.12233">pdf</a>, <a href="https://arxiv.org/format/2112.12233">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/ac97e5">10.3847/1538-4357/ac97e5 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Collimation of the relativistic jet in the quasar 3C 273 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Okino%2C+H">Hiroki Okino</a>, <a href="/search/astro-ph?searchtype=author&query=Akiyama%2C+K">Kazunori Akiyama</a>, <a href="/search/astro-ph?searchtype=author&query=Asada%2C+K">Keiichi Asada</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=Hada%2C+K">Kazuhiro Hada</a>, <a href="/search/astro-ph?searchtype=author&query=Honma%2C+M">Mareki Honma</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=Kino%2C+M">Motoki Kino</a>, <a href="/search/astro-ph?searchtype=author&query=Nagai%2C+H">Hiroshi Nagai</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">Uwe Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Blackburn%2C+L">Lindy Blackburn</a>, <a href="/search/astro-ph?searchtype=author&query=Bouman%2C+K+L">Katherine L. Bouman</a>, <a href="/search/astro-ph?searchtype=author&query=Chael%2C+A">Andrew Chael</a>, <a href="/search/astro-ph?searchtype=author&query=Crew%2C+G+B">Geoffrey B. Crew</a>, <a href="/search/astro-ph?searchtype=author&query=Doeleman%2C+S+S">Sheperd S. Doeleman</a>, <a href="/search/astro-ph?searchtype=author&query=Fish%2C+V+L">Vincent L. Fish</a>, <a href="/search/astro-ph?searchtype=author&query=Goddi%2C+C">Ciriaco Goddi</a>, <a href="/search/astro-ph?searchtype=author&query=Issaoun%2C+S">Sara Issaoun</a>, <a href="/search/astro-ph?searchtype=author&query=Johnson%2C+M+D">Michael D. Johnson</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S">Svetlana Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Koyama%2C+S">Shoko Koyama</a>, <a href="/search/astro-ph?searchtype=author&query=Lonsdale%2C+C+J">Colin J. Lonsdale</a>, <a href="/search/astro-ph?searchtype=author&query=Lu%2C+R">Ru-sen Lu</a>, <a href="/search/astro-ph?searchtype=author&query=Mart%C3%AD-Vidal%2C+I">Ivan Mart铆-Vidal</a>, <a href="/search/astro-ph?searchtype=author&query=Matthews%2C+L+D">Lynn D. Matthews</a> , et al. (10 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="2112.12233v2-abstract-short" style="display: inline;"> The collimation of relativistic jets launched from the vicinity of supermassive black holes (SMBHs) at the centers of active galactic nuclei (AGN) is one of the key questions to understand the nature of AGN jets. However, little is known about the detailed jet structure for AGN like quasars since very high angular resolutions are required to resolve these objects. We present very long baseline int… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2112.12233v2-abstract-full').style.display = 'inline'; document.getElementById('2112.12233v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2112.12233v2-abstract-full" style="display: none;"> The collimation of relativistic jets launched from the vicinity of supermassive black holes (SMBHs) at the centers of active galactic nuclei (AGN) is one of the key questions to understand the nature of AGN jets. However, little is known about the detailed jet structure for AGN like quasars since very high angular resolutions are required to resolve these objects. We present very long baseline interferometry (VLBI) observations of the archetypical quasar 3C 273 at 86 GHz, performed with the Global Millimeter VLBI Array, for the first time including the Atacama Large Millimeter/submillimeter Array. Our observations achieve a high angular resolution down to $\sim$60 ${\rm 渭}$as, resolving the innermost part of the jet ever on scales of $\sim 10^5$ Schwarzschild radii. Our observations, including close-in-time High Sensitivity Array observations of 3C 273 at 15, 22, and 43 GHz, suggest that the inner jet collimates parabolically, while the outer jet expands conically, similar to jets from other nearby low luminosity AGN. We discovered the jet collimation break around $10^{7}$ Schwarzschild radii, providing the first compelling evidence for structural transition in a quasar jet. The location of the collimation break for 3C 273 is farther downstream the sphere of gravitational influence (SGI) from the central SMBH. With the results for other AGN jets, our results show that the end of the collimation zone in AGN jets is governed not only by the SGI of the SMBH but also by the more diverse properties of the central nuclei. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2112.12233v2-abstract-full').style.display = 'none'; document.getElementById('2112.12233v2-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> 7 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 December, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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">22 pages, 13 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/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/2111.01600">arXiv:2111.01600</a> <span> [<a href="https://arxiv.org/pdf/2111.01600">pdf</a>, <a href="https://arxiv.org/format/2111.01600">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/10.3847/2041-8213/ac540f">10.3847/2041-8213/ac540f <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Milliarcsecond localisation of the repeating FRB 20201124A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Nimmo%2C+K">K. Nimmo</a>, <a href="/search/astro-ph?searchtype=author&query=Hewitt%2C+D+M">D. M. Hewitt</a>, <a href="/search/astro-ph?searchtype=author&query=Hessels%2C+J+W+T">J. W. T. Hessels</a>, <a href="/search/astro-ph?searchtype=author&query=Kirsten%2C+F">F. Kirsten</a>, <a href="/search/astro-ph?searchtype=author&query=Marcote%2C+B">B. Marcote</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Blaauw%2C+R">R. Blaauw</a>, <a href="/search/astro-ph?searchtype=author&query=Burgay%2C+M">M. Burgay</a>, <a href="/search/astro-ph?searchtype=author&query=Corongiu%2C+A">A. Corongiu</a>, <a href="/search/astro-ph?searchtype=author&query=Feiler%2C+R">R. Feiler</a>, <a href="/search/astro-ph?searchtype=author&query=Gawro%C5%84ski%2C+M+P">M. P. Gawro艅ski</a>, <a href="/search/astro-ph?searchtype=author&query=Giroletti%2C+M">M. Giroletti</a>, <a href="/search/astro-ph?searchtype=author&query=Karuppusamy%2C+R">R. Karuppusamy</a>, <a href="/search/astro-ph?searchtype=author&query=Keimpema%2C+A">A. Keimpema</a>, <a href="/search/astro-ph?searchtype=author&query=Kharinov%2C+M+A">M. A. Kharinov</a>, <a href="/search/astro-ph?searchtype=author&query=Lindqvist%2C+M">M. Lindqvist</a>, <a href="/search/astro-ph?searchtype=author&query=Maccaferri%2C+G">G. Maccaferri</a>, <a href="/search/astro-ph?searchtype=author&query=Melnikov%2C+A">A. Melnikov</a>, <a href="/search/astro-ph?searchtype=author&query=Mikhailov%2C+A">A. Mikhailov</a>, <a href="/search/astro-ph?searchtype=author&query=Ould-Boukattine%2C+O+S">O. S. Ould-Boukattine</a>, <a href="/search/astro-ph?searchtype=author&query=Paragi%2C+Z">Z. Paragi</a>, <a href="/search/astro-ph?searchtype=author&query=Pilia%2C+M">M. Pilia</a>, <a href="/search/astro-ph?searchtype=author&query=Possenti%2C+A">A. Possenti</a>, <a href="/search/astro-ph?searchtype=author&query=Snelders%2C+M+P">M. P. Snelders</a>, <a href="/search/astro-ph?searchtype=author&query=Surcis%2C+G">G. Surcis</a> , et al. (6 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="2111.01600v1-abstract-short" style="display: inline;"> Very long baseline interferometric (VLBI) localisations of repeating fast radio bursts (FRBs) have demonstrated a diversity of local environments: from nearby star-forming regions to globular clusters. Here we report the VLBI localisation of FRB 20201124A using an ad-hoc array of dishes that also participate in the European VLBI Network (EVN). In our campaign, we detected 18 total bursts from FRB… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.01600v1-abstract-full').style.display = 'inline'; document.getElementById('2111.01600v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2111.01600v1-abstract-full" style="display: none;"> Very long baseline interferometric (VLBI) localisations of repeating fast radio bursts (FRBs) have demonstrated a diversity of local environments: from nearby star-forming regions to globular clusters. Here we report the VLBI localisation of FRB 20201124A using an ad-hoc array of dishes that also participate in the European VLBI Network (EVN). In our campaign, we detected 18 total bursts from FRB 20201124A at two separate epochs. By combining the visibilities from both observing epochs, we were able to localise FRB 20201124A with a 1-$蟽$ error of 4.5 milliarcseconds (mas). We use the relatively large burst sample to investigate astrometric accuracy, and find that for $\gtrsim20$ baselines ($\gtrsim7$ dishes) that we can robustly reach milliarcsecond precision even using single-burst data sets. Sub-arcsecond precision is still possible for single bursts, even when only $\sim$ six baselines (four dishes) are available. We explore two methods for determining the individual burst positions: the peaks of the dirty maps and a Gaussian fit to the cross fringe pattern on the dirty maps. We found the latter to be more reliable due to the lower mean and standard deviation in the offsets from the FRB position. Our VLBI work places FRB 20201124A 705$\pm$26 mas (1-$蟽$ errors) from the optical centre of the host galaxy, and consistent with originating from within the recently-discovered extended radio structure associated with star-formation in the host galaxy. Future high-resolution optical observations, e.g. with Hubble Space Telescope, can determine the proximity of our FRB 20201124A VLBI position to nearby knots of star formation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.01600v1-abstract-full').style.display = 'none'; document.getElementById('2111.01600v1-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, 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">Comments:</span> <span class="has-text-grey-dark mathjax">submitted, comments welcome</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2109.00006">arXiv:2109.00006</a> <span> [<a href="https://arxiv.org/pdf/2109.00006">pdf</a>, <a href="https://arxiv.org/format/2109.00006">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</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/10.1051/0004-6361/202142116">10.1051/0004-6361/202142116 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Out-of-focus holography at the Effelsberg telescope </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Cassanelli%2C+T">T. Cassanelli</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Winkel%2C+B">B. Winkel</a>, <a href="/search/astro-ph?searchtype=author&query=Kraus%2C+A">A. Kraus</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="2109.00006v2-abstract-short" style="display: inline;"> Out-of-focus (OOF) holography can be used to determine aperture deformations of radio telescopes that lead to errors in the phase of the complex aperture distribution. In contrast to traditional methods, OOF holography can be performed without a reference antenna, which has a number of practical advantages. The aim of this work is to develop a standard procedure for OOF holography at the Effelsber… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.00006v2-abstract-full').style.display = 'inline'; document.getElementById('2109.00006v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2109.00006v2-abstract-full" style="display: none;"> Out-of-focus (OOF) holography can be used to determine aperture deformations of radio telescopes that lead to errors in the phase of the complex aperture distribution. In contrast to traditional methods, OOF holography can be performed without a reference antenna, which has a number of practical advantages. The aim of this work is to develop a standard procedure for OOF holography at the Effelsberg telescope. This includes performing OOF holography observations and the development of a dedicated software, the pyoof package, to compute aberrations of the telescope's optical system. Based on the OOF holography method developed at the Green Bank telescope, we adapted the approach to the Effelsberg 100-m telescope in order to determine the aberrations of the aperture phase distribution (phase-error maps). The developed OOF holography software is presented as well as the results from observations at Effelsberg. Early results reveal gravitationally-caused residual deformation not contained in the previously existing aperture and pointing model, and hence we propose to make changes to the model to counteract aberrations in the telescope's surface. The OOF holography method (observations and pyoof package) works as expected at the Effelsberg 100-m telescope and is able to validate the good performance of the existing finite element model. Test measurements show that slight improvements of the aperture efficiency and gain elevation dependence are possible but limited in the current configuration. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.00006v2-abstract-full').style.display = 'none'; document.getElementById('2109.00006v2-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 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 31 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 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 Astronomy & Astrophysics (A&A) 19 figures, 6 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 687, A27 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2108.00383">arXiv:2108.00383</a> <span> [<a href="https://arxiv.org/pdf/2108.00383">pdf</a>, <a href="https://arxiv.org/format/2108.00383">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"> TELAMON: Effelsberg Monitoring of AGN Jets with Very-High-Energy Astroparticle Emissions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kadler%2C+M">M. Kadler</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Berge%2C+D">D. Berge</a>, <a href="/search/astro-ph?searchtype=author&query=Buson%2C+S">S. Buson</a>, <a href="/search/astro-ph?searchtype=author&query=Dorner%2C+D">D. Dorner</a>, <a href="/search/astro-ph?searchtype=author&query=Edwards%2C+P+G">P. G. Edwards</a>, <a href="/search/astro-ph?searchtype=author&query=Eppel%2C+F">F. Eppel</a>, <a href="/search/astro-ph?searchtype=author&query=Giroletti%2C+M">M. Giroletti</a>, <a href="/search/astro-ph?searchtype=author&query=Gokus%2C+A">A. Gokus</a>, <a href="/search/astro-ph?searchtype=author&query=Hervet%2C+O">O. Hervet</a>, <a href="/search/astro-ph?searchtype=author&query=He%C3%9Fd%C3%B6rfer%2C+J">J. He脽d枚rfer</a>, <a href="/search/astro-ph?searchtype=author&query=Koyama%2C+S">S. Koyama</a>, <a href="/search/astro-ph?searchtype=author&query=Kraus%2C+A">A. Kraus</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=Lindfors%2C+E">E. Lindfors</a>, <a href="/search/astro-ph?searchtype=author&query=Mannheim%2C+K">K. Mannheim</a>, <a href="/search/astro-ph?searchtype=author&query=de+Menezes%2C+R">R. de Menezes</a>, <a href="/search/astro-ph?searchtype=author&query=Ojha%2C+R">R. Ojha</a>, <a href="/search/astro-ph?searchtype=author&query=Paraschos%2C+G+F">G. F. Paraschos</a>, <a href="/search/astro-ph?searchtype=author&query=Pueschel%2C+E">E. Pueschel</a>, <a href="/search/astro-ph?searchtype=author&query=R%C3%B6sch%2C+F">F. R枚sch</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">E. Ros</a>, <a href="/search/astro-ph?searchtype=author&query=Schleicher%2C+B">B. Schleicher</a>, <a href="/search/astro-ph?searchtype=author&query=Sinapius%2C+J">J. Sinapius</a>, <a href="/search/astro-ph?searchtype=author&query=Sitarek%2C+J">J. Sitarek</a> , et al. (2 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="2108.00383v1-abstract-short" style="display: inline;"> We introduce the TELAMON program, which is using the Effelsberg 100-m telescope to monitor the radio spectra of active galactic nuclei (AGN) under scrutiny in astroparticle physics, namely TeV blazars and candidate neutrino-associated AGN. Thanks to its large dish aperture and sensitive instrumentation, the Effelsberg telescope can yield radio data superior over other programs in the low flux-dens… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.00383v1-abstract-full').style.display = 'inline'; document.getElementById('2108.00383v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2108.00383v1-abstract-full" style="display: none;"> We introduce the TELAMON program, which is using the Effelsberg 100-m telescope to monitor the radio spectra of active galactic nuclei (AGN) under scrutiny in astroparticle physics, namely TeV blazars and candidate neutrino-associated AGN. Thanks to its large dish aperture and sensitive instrumentation, the Effelsberg telescope can yield radio data superior over other programs in the low flux-density regime down to several 10 mJy. This is a particular strength in the case of TeV-emitting blazars, which are often comparatively faint radio sources of the high-synchrotron peaked type. We perform high-cadence high-frequency observations every 2-4 weeks at multiple frequencies up to 44 GHz. This setup is well suited to trace dynamical processes in the compact parsec-scale jets of blazars related to high-energy flares or neutrino detections. Our sample currently covers about 40 sources and puts its focus on AGN with very-high-energy astroparticle emission, i.e., TeV blazars and neutrino-associated AGN. Here, we introduce the TELAMON program characteristics and present first results obtained since fall 2020. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.00383v1-abstract-full').style.display = 'none'; document.getElementById('2108.00383v1-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 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 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">8 pages, 5 figures, Proceedings of the 37th International Cosmic Ray Conference (ICRC2021). 12-23 July, 2021. Berlin, Germany. Online at https://pos.sissa.it/395/</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2107.00083">arXiv:2107.00083</a> <span> [<a href="https://arxiv.org/pdf/2107.00083">pdf</a>, <a href="https://arxiv.org/format/2107.00083">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"> Project MOMO: Multiwavelength Observations and Modelling of OJ 287 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Komossa%2C+S">S. Komossa</a>, <a href="/search/astro-ph?searchtype=author&query=Grupe%2C+D">D. Grupe</a>, <a href="/search/astro-ph?searchtype=author&query=Kraus%2C+A">A. Kraus</a>, <a href="/search/astro-ph?searchtype=author&query=Gallo%2C+L+C">L. C. Gallo</a>, <a href="/search/astro-ph?searchtype=author&query=Gonzalez%2C+A">A. Gonzalez</a>, <a href="/search/astro-ph?searchtype=author&query=Parker%2C+M+L">M. L. Parker</a>, <a href="/search/astro-ph?searchtype=author&query=Valtonen%2C+M+J">M. J. Valtonen</a>, <a href="/search/astro-ph?searchtype=author&query=Hollett%2C+A+R">A. R. Hollett</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</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=Myserlis%2C+I">I. Myserlis</a>, <a href="/search/astro-ph?searchtype=author&query=Ciprini%2C+S">S. Ciprini</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="2107.00083v1-abstract-short" style="display: inline;"> Our project MOMO (Multiwavelength observations and modelling of OJ 287) consists of dedicated, dense, long-term flux and spectroscopic monitoring and deep follow-up observations of the blazar OJ 287 at >13 frequencies from the radio to the X-ray band since late 2015. In particular, we are using Swift to obtain optical-UV-X-ray spectral energy distributions (SEDs) and the Effelsberg telescope to ob… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.00083v1-abstract-full').style.display = 'inline'; document.getElementById('2107.00083v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2107.00083v1-abstract-full" style="display: none;"> Our project MOMO (Multiwavelength observations and modelling of OJ 287) consists of dedicated, dense, long-term flux and spectroscopic monitoring and deep follow-up observations of the blazar OJ 287 at >13 frequencies from the radio to the X-ray band since late 2015. In particular, we are using Swift to obtain optical-UV-X-ray spectral energy distributions (SEDs) and the Effelsberg telescope to obtain radio measurements between 2 and 40 GHz. MOMO is the densest long-term monitoring of OJ 287 involving X-rays and broad-band SEDs. The theoretical part of the project aims at understanding jet and accretion physics of the blazar central engine in general and the supermassive binary black hole scenario in particular. Results are presented in a sequence of publications and so far included: detection and detailed analysis of the bright 2016/17 and 2020 outbursts and the long-term light curve; Swift, XMM and NuSTAR spectroscopy of the 2020 outburst around maximum; and interpretation of selected events in the context of the binary black hole scenario of OJ 287 (papers I-IV). Here, we provide a description of the project MOMO, a summary of previous results, the latest results, and we discuss future prospects. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.00083v1-abstract-full').style.display = 'none'; document.getElementById('2107.00083v1-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 June, 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">Review. 18 pages, 11 figures. Submitted to Universe Special Issue "Panchromatic View of the Life-Cycle of AGN"</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2105.11445">arXiv:2105.11445</a> <span> [<a href="https://arxiv.org/pdf/2105.11445">pdf</a>, <a href="https://arxiv.org/format/2105.11445">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/10.1038/s41586-021-04354-w">10.1038/s41586-021-04354-w <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A repeating fast radio burst source in a globular cluster </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kirsten%2C+F">F. Kirsten</a>, <a href="/search/astro-ph?searchtype=author&query=Marcote%2C+B">B. Marcote</a>, <a href="/search/astro-ph?searchtype=author&query=Nimmo%2C+K">K. Nimmo</a>, <a href="/search/astro-ph?searchtype=author&query=Hessels%2C+J+W+T">J. W. T. Hessels</a>, <a href="/search/astro-ph?searchtype=author&query=Bhardwaj%2C+M">M. Bhardwaj</a>, <a href="/search/astro-ph?searchtype=author&query=Tendulkar%2C+S+P">S. P. Tendulkar</a>, <a href="/search/astro-ph?searchtype=author&query=Keimpema%2C+A">A. Keimpema</a>, <a href="/search/astro-ph?searchtype=author&query=Yang%2C+J">J. Yang</a>, <a href="/search/astro-ph?searchtype=author&query=Snelders%2C+M+P">M. P. Snelders</a>, <a href="/search/astro-ph?searchtype=author&query=Scholz%2C+P">P. Scholz</a>, <a href="/search/astro-ph?searchtype=author&query=Pearlman%2C+A+B">A. B. Pearlman</a>, <a href="/search/astro-ph?searchtype=author&query=Law%2C+C+J">C. J. Law</a>, <a href="/search/astro-ph?searchtype=author&query=Peters%2C+W+M">W. M. Peters</a>, <a href="/search/astro-ph?searchtype=author&query=Giroletti%2C+M">M. Giroletti</a>, <a href="/search/astro-ph?searchtype=author&query=Paragi%2C+Z">Z. Paragi</a>, <a href="/search/astro-ph?searchtype=author&query=Bassa%2C+C">C. Bassa</a>, <a href="/search/astro-ph?searchtype=author&query=Hewitt%2C+D+M">D. M. Hewitt</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Bezrukovs%2C+V">V. Bezrukovs</a>, <a href="/search/astro-ph?searchtype=author&query=Burgay%2C+M">M. Burgay</a>, <a href="/search/astro-ph?searchtype=author&query=Buttaccio%2C+S+T">S. T. Buttaccio</a>, <a href="/search/astro-ph?searchtype=author&query=Conway%2C+J+E">J. E. Conway</a>, <a href="/search/astro-ph?searchtype=author&query=Corongiu%2C+A">A. Corongiu</a>, <a href="/search/astro-ph?searchtype=author&query=Feiler%2C+R">R. Feiler</a>, <a href="/search/astro-ph?searchtype=author&query=Forss%C3%A9n%2C+O">O. Forss茅n</a> , et al. (41 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="2105.11445v2-abstract-short" style="display: inline;"> Fast radio bursts (FRBs) are exceptionally luminous flashes of unknown physical origin, reaching us from other galaxies (Petroff et al. 2019). Most FRBs have only ever been seen once, while others flash repeatedly, though sporadically (Spitler et al. 2016, CHIME/FRB Collaboration et al. 2021). Many models invoke magnetically powered neutron stars (magnetars) as the engines producing FRB emission (… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.11445v2-abstract-full').style.display = 'inline'; document.getElementById('2105.11445v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2105.11445v2-abstract-full" style="display: none;"> Fast radio bursts (FRBs) are exceptionally luminous flashes of unknown physical origin, reaching us from other galaxies (Petroff et al. 2019). Most FRBs have only ever been seen once, while others flash repeatedly, though sporadically (Spitler et al. 2016, CHIME/FRB Collaboration et al. 2021). Many models invoke magnetically powered neutron stars (magnetars) as the engines producing FRB emission (Margalit & Metzger 2018, CHIME/FRB Collaboration et al. 2020). Recently, CHIME/FRB announced the discovery (Bhardwaj et al. 2021) of the repeating FRB 20200120E, coming from the direction of the nearby grand design spiral galaxy M81. Four potential counterparts at other observing wavelengths were identified (Bhardwaj et al. 2021) but no definitive association with these sources, or M81, could be made. Here we report an extremely precise localisation of FRB 20200120E, which allows us to associate it with a globular cluster (GC) in the M81 galactic system and to place it ~2pc offset from the optical center of light of the GC. This confirms (Bhardwaj et al. 2021) that FRB 20200120E is 40 times closer than any other known extragalactic FRB. Because such GCs host old stellar populations, this association strongly challenges FRB models that invoke young magnetars formed in a core-collapse supernova as powering FRB emission. We propose, instead, that FRB 20200120E is a highly magnetised neutron star formed via either accretion-induced collapse of a white dwarf or via merger of compact stars in a binary system (Margalit et al. 2019). Alternative scenarios involving compact binary systems, efficiently formed inside globular clusters, could also be responsible for the observed bursts. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.11445v2-abstract-full').style.display = 'none'; document.getElementById('2105.11445v2-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 September, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 May, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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">Submitted. Comments welcome</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2102.04441">arXiv:2102.04441</a> <span> [<a href="https://arxiv.org/pdf/2102.04441">pdf</a>, <a href="https://arxiv.org/format/2102.04441">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/10.1051/0004-6361/202039493">10.1051/0004-6361/202039493 <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 IV. The quasar 3C 345 at 18 cm: Magnetic field structure and brightness temperature </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=Lobanov%2C+A+P">A. P. Lobanov</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">E. Ros</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=Bruni%2C+G">G. Bruni</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Fuentes%2C+A">A. Fuentes</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=Jauncey%2C+D+L">D. L. Jauncey</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=Kravchenko%2C+E+V">E. V. Kravchenko</a>, <a href="/search/astro-ph?searchtype=author&query=Lisakov%2C+M+M">M. M. Lisakov</a>, <a href="/search/astro-ph?searchtype=author&query=Savolainen%2C+T">T. Savolainen</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=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="2102.04441v1-abstract-short" style="display: inline;"> Context. Supermassive black holes in the centres of radio-loud active galactic nuclei (AGN) can produce collimated relativistic outflows (jets). Magnetic fields are thought to play a key role in the formation and collimation of these jets, but the details are much debated. Aims. We study the innermost jet morphology and magnetic field strength in the AGN 3C 345 with an unprecedented resolution usi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.04441v1-abstract-full').style.display = 'inline'; document.getElementById('2102.04441v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2102.04441v1-abstract-full" style="display: none;"> Context. Supermassive black holes in the centres of radio-loud active galactic nuclei (AGN) can produce collimated relativistic outflows (jets). Magnetic fields are thought to play a key role in the formation and collimation of these jets, but the details are much debated. Aims. We study the innermost jet morphology and magnetic field strength in the AGN 3C 345 with an unprecedented resolution using images obtained within the framework of the key science programme on AGN polarisation of the Space VLBI mission RadioAstron. Methods. We observed the flat spectrum radio quasar 3C 345 at 1.6 GHz on 2016 March 30 with RadioAstron and 18 ground-based radio telescopes in full polarisation mode. Results. Our images, in both total intensity and linear polarisation, reveal a complex jet structure at 300 $渭$as angular resolution, corresponding to a projected linear scale of about 2 pc or a few thousand gravitational radii. We identify the synchrotron self-absorbed core at the jet base and find the brightest feature in the jet 1.5 mas downstream of the core. Several polarised components appear in the Space VLBI images that cannot be seen from ground array-only images. Except for the core, the electric vector position angles follow the local jet direction, suggesting a magnetic field perpendicular to the jet. This indicates the presence of plane perpendicular shocks in these regions. Additionally, we infer a minimum brightness temperature at the largest $(u,v)$-distances of $1.1\times 10^{12}$ K in the source frame, which is above the inverse Compton limit and an order of magnitude larger than the equipartition value. This indicates locally efficient injection or re-acceleration of particles in the jet to counter the inverse Compton cooling or the geometry of the jet creates significant changes in the Doppler factor, which has to be $>11$ to explain the high brightness temperatures. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.04441v1-abstract-full').style.display = 'none'; document.getElementById('2102.04441v1-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> 8 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, 9 figures. Accepted for publication 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 648, A82 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2012.14831">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/1912.00776">arXiv:1912.00776</a> <span> [<a href="https://arxiv.org/pdf/1912.00776">pdf</a>, <a href="https://arxiv.org/format/1912.00776">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/10.1051/0004-6361/201935756">10.1051/0004-6361/201935756 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Localizing the $纬$-ray emitting region in the blazar TXS 2013+370 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Traianou%2C+E">E. Traianou</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=Boccardi%2C+B">B. Boccardi</a>, <a href="/search/astro-ph?searchtype=author&query=Angioni%2C+R">R. Angioni</a>, <a href="/search/astro-ph?searchtype=author&query=Rani%2C+B">B. Rani</a>, <a href="/search/astro-ph?searchtype=author&query=Liu%2C+J">J. Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">E. Ros</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</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=Kiehlmann%2C+S">S. Kiehlmann</a>, <a href="/search/astro-ph?searchtype=author&query=Gurwell%2C+M">M. Gurwell</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="1912.00776v2-abstract-short" style="display: inline;"> The $纬$-ray production mechanism and its localization in blazars are still a matter of debate. The main goal of this paper is to constrain the location of the high-energy emission in the blazar TXS 2013+370 and to study the physical and geometrical properties of the inner jet region on sub-pc scales. VLBI observations at 86 GHz and space-VLBI at 22 GHz allowed us to image the jet base with an angu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.00776v2-abstract-full').style.display = 'inline'; document.getElementById('1912.00776v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.00776v2-abstract-full" style="display: none;"> The $纬$-ray production mechanism and its localization in blazars are still a matter of debate. The main goal of this paper is to constrain the location of the high-energy emission in the blazar TXS 2013+370 and to study the physical and geometrical properties of the inner jet region on sub-pc scales. VLBI observations at 86 GHz and space-VLBI at 22 GHz allowed us to image the jet base with an angular resolution of $\sim$0.4 pc. By employing CLEAN imaging and Gaussian model-fitting, we performed a thorough kinematic analysis, which provided estimates of the jet speed, orientation, and component ejection times. Additionally, we studied the jet expansion profile and used the information on the jet geometry to estimate the location of the jet apex. VLBI data were combined with single-dish measurements to search for correlated activity between the radio and $纬$-ray emission. The high-resolution VLBI imaging revealed the existence of a spatially bent jet, described by moving and stationary features. New jet features are observed to emerge from the core, accompanied by flaring activity in radio bands and $纬$ rays. The analysis of the transverse jet width profile constrains the location of the mm core to lie $\leq$ 2 pc downstream of the jet apex, and also reveals the existence of a transition from parabolic to conical jet expansion at a distance of $\sim$54 pc from the core, corresponding to $\sim$1.5$\times$10$^{\rm 6}$ Schwarzschild radii. The cross-correlation analysis reveals a strong correlation between the radio and $纬$-ray data, with the 1 mm emission lagging $\sim$49 days behind the $纬$ rays. Based on this, we infer that the high energy emission is produced at a distance of $\sim$1 pc from the VLBI core, suggesting that the seed photon fields for the external Compton mechanism originate either in the dusty torus or in the broad-line region. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.00776v2-abstract-full').style.display = 'none'; document.getElementById('1912.00776v2-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 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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">16 pages, 15 figures, accepted 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 634, A112 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1901.06226">arXiv:1901.06226</a> <span> [<a href="https://arxiv.org/pdf/1901.06226">pdf</a>, <a href="https://arxiv.org/format/1901.06226">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/aaf732">10.3847/1538-4357/aaf732 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The Size, Shape, and Scattering of Sagittarius A* at 86 GHz: First VLBI with ALMA </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Issaoun%2C+S">S. Issaoun</a>, <a href="/search/astro-ph?searchtype=author&query=Johnson%2C+M+D">M. D. Johnson</a>, <a href="/search/astro-ph?searchtype=author&query=Blackburn%2C+L">L. Blackburn</a>, <a href="/search/astro-ph?searchtype=author&query=Brinkerink%2C+C+D">C. D. Brinkerink</a>, <a href="/search/astro-ph?searchtype=author&query=Mo%C5%9Bcibrodzka%2C+M">M. Mo艣cibrodzka</a>, <a href="/search/astro-ph?searchtype=author&query=Chael%2C+A">A. Chael</a>, <a href="/search/astro-ph?searchtype=author&query=Goddi%2C+C">C. Goddi</a>, <a href="/search/astro-ph?searchtype=author&query=Mart%C3%AD-Vidal%2C+I">I. Mart铆-Vidal</a>, <a href="/search/astro-ph?searchtype=author&query=Wagner%2C+J">J. Wagner</a>, <a href="/search/astro-ph?searchtype=author&query=Doeleman%2C+S+S">S. S. Doeleman</a>, <a href="/search/astro-ph?searchtype=author&query=Falcke%2C+H">H. Falcke</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=Akiyama%2C+K">K. Akiyama</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Bouman%2C+K+L">K. L. Bouman</a>, <a href="/search/astro-ph?searchtype=author&query=Bower%2C+G+C">G. C. Bower</a>, <a href="/search/astro-ph?searchtype=author&query=Broderick%2C+A">A. Broderick</a>, <a href="/search/astro-ph?searchtype=author&query=Cho%2C+I">I. Cho</a>, <a href="/search/astro-ph?searchtype=author&query=Crew%2C+G">G. Crew</a>, <a href="/search/astro-ph?searchtype=author&query=Dexter%2C+J">J. Dexter</a>, <a href="/search/astro-ph?searchtype=author&query=Fish%2C+V">V. Fish</a>, <a href="/search/astro-ph?searchtype=author&query=Gold%2C+R">R. Gold</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=Hada%2C+K">K. Hada</a>, <a href="/search/astro-ph?searchtype=author&query=Hern%C3%A1ndez-G%C3%B3mez%2C+A">A. Hern谩ndez-G贸mez</a> , et al. (19 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="1901.06226v1-abstract-short" style="display: inline;"> The Galactic Center supermassive black hole Sagittarius A* (Sgr A*) is one of the most promising targets to study the dynamics of black hole accretion and outflow via direct imaging with very long baseline interferometry (VLBI). At 3.5 mm (86 GHz), the emission from Sgr A* is resolvable with the Global Millimeter VLBI Array (GMVA). We present the first observations of Sgr A* with the phased Atacam… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1901.06226v1-abstract-full').style.display = 'inline'; document.getElementById('1901.06226v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1901.06226v1-abstract-full" style="display: none;"> The Galactic Center supermassive black hole Sagittarius A* (Sgr A*) is one of the most promising targets to study the dynamics of black hole accretion and outflow via direct imaging with very long baseline interferometry (VLBI). At 3.5 mm (86 GHz), the emission from Sgr A* is resolvable with the Global Millimeter VLBI Array (GMVA). We present the first observations of Sgr A* with the phased Atacama Large Millimeter/submillimeter Array (ALMA) joining the GMVA. Our observations achieve an angular resolution of ~87渭as, improving upon previous experiments by a factor of two. We reconstruct a first image of the unscattered source structure of Sgr A* at 3.5 mm, mitigating effects of interstellar scattering. The unscattered source has a major axis size of 120 $\pm$ 34渭as (12 $\pm$ 3.4 Schwarzschild radii), and a symmetrical morphology (axial ratio of 1.2$^{+0.3}_{-0.2}$), which is further supported by closure phases consistent with zero within 3蟽. We show that multiple disk-dominated models of Sgr A* match our observational constraints, while the two jet-dominated models considered are constrained to small viewing angles. Our long-baseline detections to ALMA also provide new constraints on the scattering of Sgr A*, and we show that refractive scattering effects are likely to be weak for images of Sgr A* at 1.3 mm with the Event Horizon Telescope. Our results provide the most stringent constraints to date for the intrinsic morphology and refractive scattering of Sgr A*, demonstrating the exceptional contribution of ALMA to millimeter VLBI. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1901.06226v1-abstract-full').style.display = 'none'; document.getElementById('1901.06226v1-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 January, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 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">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/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/1809.01663">arXiv:1809.01663</a> <span> [<a href="https://arxiv.org/pdf/1809.01663">pdf</a>, <a href="https://arxiv.org/ps/1809.01663">ps</a>, <a href="https://arxiv.org/format/1809.01663">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> <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/10.1051/0004-6361/201732273">10.1051/0004-6361/201732273 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> High cadence, linear and circular polarization monitoring of OJ 287 - Helical magnetic field in a bent jet </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Myserlis%2C+I">I. Myserlis</a>, <a href="/search/astro-ph?searchtype=author&query=Komossa%2C+S">S. Komossa</a>, <a href="/search/astro-ph?searchtype=author&query=Angelakis%2C+E">E. Angelakis</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=Karamanavis%2C+V">V. Karamanavis</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=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Grupe%2C+D">D. Grupe</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="1809.01663v1-abstract-short" style="display: inline;"> We present a multi-frequency, dense radio monitoring program of the blazar OJ287 using the 100m Effelsberg radio telescope. We analyze the evolution in total flux density, linear and circular polarization to study the jet structure and its magnetic field geometry. The total flux density is measured at nine bands from 2.64 GHz to 43 GHz, the linear polarization parameters between 2.64 GHz and 10.45… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1809.01663v1-abstract-full').style.display = 'inline'; document.getElementById('1809.01663v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1809.01663v1-abstract-full" style="display: none;"> We present a multi-frequency, dense radio monitoring program of the blazar OJ287 using the 100m Effelsberg radio telescope. We analyze the evolution in total flux density, linear and circular polarization to study the jet structure and its magnetic field geometry. The total flux density is measured at nine bands from 2.64 GHz to 43 GHz, the linear polarization parameters between 2.64 GHz and 10.45 GHz, and the circular polarization at 4.85 GHz and 8.35 GHz. The mean cadence is 10 days. Between MJD 57370 and 57785, OJ287 showed flaring activity and complex linear and circular polarization behavior. The radio EVPA showed a large clockwise (CW) rotation by ~340$^{\circ}$ with a mean rate of -1.04 $^{\circ}$/day. Based on concurrent VLBI data, the rotation seems to originate within the jet core at 43 GHz (projected size $\le$ 0.15 mas or 0.67 pc). Moreover, optical data show a similar monotonic CW EVPA rotation with a rate of about -1.1 $^{\circ}$/day which is superposed with shorter and faster rotations of about 7.8 $^{\circ}$/day. The observed variability is consistent with a polarized emission component propagating on a helical trajectory within a bent jet. We constrained the helix arc length to 0.26 pc and radius to $\le$ 0.04 pc as well as the jet bending arc length projected on the plane of the sky to $\le$ 1.9-7.6 pc. A similar bending is observed in high angular resolution VLBI images at the innermost jet regions. Our results indicate also the presence of a stable polarized emission component with EVPA (-10$^{\circ}$) perpendicular to the large scale jet, suggesting dominance of the poloidal magnetic field component. Finally, the EVPA rotation begins simultaneously with an optical flare and hence the two might be physically connected. That optical flare has been linked to the interaction of a secondary SMBH with the inner accretion disk or originating in the jet of the primary. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1809.01663v1-abstract-full').style.display = 'none'; document.getElementById('1809.01663v1-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 September, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 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">11 pages, 9 figures, 1 table, accepted for publication in section 4. Extragalactic astronomy of Astronomy and Astrophysics on August 21, 2018</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 619, A88 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1805.02478">arXiv:1805.02478</a> <span> [<a href="https://arxiv.org/pdf/1805.02478">pdf</a>, <a href="https://arxiv.org/format/1805.02478">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/10.1051/0004-6361/201832921">10.1051/0004-6361/201832921 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The limb-brightened jet of M87 down to 7 Schwarzschild radii scale </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kim%2C+J+-">J. -Y. Kim</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=Lu%2C+R+-">R. -S. Lu</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">E. Ros</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Bremer%2C+M">M. Bremer</a>, <a href="/search/astro-ph?searchtype=author&query=de+Vicente%2C+P">P. de Vicente</a>, <a href="/search/astro-ph?searchtype=author&query=Lindqvist%2C+M">M. Lindqvist</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="1805.02478v1-abstract-short" style="display: inline;"> M87 is one of the nearest radio galaxies with a prominent jet extending from sub-pc to kpc-scales. Because of its proximity and large mass of the central black hole, it is one of the best radio sources to study jet formation. We aim at studying the physical conditions near the jet base at projected separations from the BH of $\sim7-100$ Schwarzschild radii ($R_{\rm sch}$). Global mm-VLBI Array (GM… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1805.02478v1-abstract-full').style.display = 'inline'; document.getElementById('1805.02478v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1805.02478v1-abstract-full" style="display: none;"> M87 is one of the nearest radio galaxies with a prominent jet extending from sub-pc to kpc-scales. Because of its proximity and large mass of the central black hole, it is one of the best radio sources to study jet formation. We aim at studying the physical conditions near the jet base at projected separations from the BH of $\sim7-100$ Schwarzschild radii ($R_{\rm sch}$). Global mm-VLBI Array (GMVA) observations at 86 GHz ($位=3.5\,$mm) provide an angular resolution of $\sim50渭$as, which corresponds to a spatial resolution of only $7~R_{\rm sch}$ and reach the small spatial scale. We use five GMVA data sets of M87 obtained during 2004--2015 and present new high angular resolution VLBI maps at 86GHz. In particular, we focus on the analysis of the brightness temperature, the jet ridge lines, and the jet to counter-jet ratio. The imaging reveals a parabolically expanding limb-brightened jet which emanates from a resolved VLBI core of $\sim(8-13) R_{\rm sch}$ size. The observed brightness temperature of the core at any epoch is $\sim(1-3)\times10^{10}\,$K, which is below the equipartition brightness temperature and suggests magnetic energy dominance at the jet base. We estimate the diameter of the jet at its base to be $\sim5 R_{\rm sch}$ assuming a self-similar jet structure. This suggests that the sheath of the jet may be anchored in the very inner portion of the accretion disk. The image stacking reveals faint emission at the center of the edge-brightened jet on sub-pc scales. We discuss its physical implication within the context of the spine-sheath structure of the jet. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1805.02478v1-abstract-full').style.display = 'none'; document.getElementById('1805.02478v1-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> 7 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">13 pages, 12 figures, accepted for a 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 616, A188 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1804.05640">arXiv:1804.05640</a> <span> [<a href="https://arxiv.org/pdf/1804.05640">pdf</a>, <a href="https://arxiv.org/format/1804.05640">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Earth and Planetary Astrophysics">astro-ph.EP</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/10.3847/1538-3881/aad45b">10.3847/1538-3881/aad45b <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Radio interferometric observation of an asteroid occultation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Harju%2C+J">Jorma Harju</a>, <a href="/search/astro-ph?searchtype=author&query=Lehtinen%2C+K">Kimmo Lehtinen</a>, <a href="/search/astro-ph?searchtype=author&query=Romney%2C+J">Jonathan Romney</a>, <a href="/search/astro-ph?searchtype=author&query=Petrov%2C+L">Leonid Petrov</a>, <a href="/search/astro-ph?searchtype=author&query=Granvik%2C+M">Mikael Granvik</a>, <a href="/search/astro-ph?searchtype=author&query=Muinonen%2C+K">Karri Muinonen</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">Uwe Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+M">Markku Poutanen</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="1804.05640v2-abstract-short" style="display: inline;"> The occultation of the radio galaxy 0141+268 by the asteroid (372) Palma on 2017 May 15 was observed using six antennas of the Very Long Baseline Array (VLBA). The shadow of Palma crossed the VLBA station at Brewster, Washington. Owing to the wavelength used, and the size and the distance of the asteroid, a diffraction pattern in the Fraunhofer regime was observed. The measurement retrieves both t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1804.05640v2-abstract-full').style.display = 'inline'; document.getElementById('1804.05640v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1804.05640v2-abstract-full" style="display: none;"> The occultation of the radio galaxy 0141+268 by the asteroid (372) Palma on 2017 May 15 was observed using six antennas of the Very Long Baseline Array (VLBA). The shadow of Palma crossed the VLBA station at Brewster, Washington. Owing to the wavelength used, and the size and the distance of the asteroid, a diffraction pattern in the Fraunhofer regime was observed. The measurement retrieves both the amplitude and the phase of the diffracted electromagnetic wave. This is the first astronomical measurement of the phase shift caused by diffraction. The maximum phase shift is sensitive to the effective diameter of the asteroid. The bright spot at the shadow's center, the so called Arago--Poisson spot, is clearly detected in the amplitude time-series, and its strength is a good indicator of the closest angular distance between the center of the asteroid and the radio source. A sample of random shapes constructed using a Markov chain Monte Carlo algorithm suggests that the silhouette of Palma deviates from a perfect circle by 26+-13%. The best-fitting random shapes resemble each other, and we suggest their average approximates the shape of the silhouette at the time of the occultation. The effective diameter obtained for Palma, 192.1+-4.8 km, is in excellent agreement with recent estimates from thermal modeling of mid-infrared photometry. Finally, our computations show that because of the high positional accuracy, a single radio interferometric occultation measurement can reduce the long-term ephemeris uncertainty by an order of magnitude. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1804.05640v2-abstract-full').style.display = 'none'; document.getElementById('1804.05640v2-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> 13 September, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 16 April, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">13 pages, 10 figures, to appear in the Astronomical 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/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/1711.06713">arXiv:1711.06713</a> <span> [<a href="https://arxiv.org/pdf/1711.06713">pdf</a>, <a href="https://arxiv.org/format/1711.06713">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/stx2991">10.1093/mnras/stx2991 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The high brightness temperature of B0529+483 revealed by RadioAstron and implications for interstellar scattering </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Pilipenko%2C+S+V">S. V. Pilipenko</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=Andrianov%2C+A+S">A. S. Andrianov</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Buttaccio%2C+S">S. Buttaccio</a>, <a href="/search/astro-ph?searchtype=author&query=Cassaro%2C+P">P. Cassaro</a>, <a href="/search/astro-ph?searchtype=author&query=Cim%C3%B2%2C+G">G. Cim貌</a>, <a href="/search/astro-ph?searchtype=author&query=Edwards%2C+P+G">P. G. Edwards</a>, <a href="/search/astro-ph?searchtype=author&query=Gawro%C5%84ski%2C+M+P">M. P. Gawro艅ski</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=Hovatta%2C+T">T. Hovatta</a>, <a href="/search/astro-ph?searchtype=author&query=Jauncey%2C+D+L">D. L. Jauncey</a>, <a href="/search/astro-ph?searchtype=author&query=Johnson%2C+M+D">M. D. Johnson</a>, <a href="/search/astro-ph?searchtype=author&query=Kovalev%2C+Y+A">Yu. A. Kovalev</a>, <a href="/search/astro-ph?searchtype=author&query=Kutkin%2C+A+M">A. M. Kutkin</a>, <a href="/search/astro-ph?searchtype=author&query=Lisakov%2C+M+M">M. M. Lisakov</a>, <a href="/search/astro-ph?searchtype=author&query=Melnikov%2C+A+E">A. E. Melnikov</a>, <a href="/search/astro-ph?searchtype=author&query=Orlati%2C+A">A. Orlati</a>, <a href="/search/astro-ph?searchtype=author&query=Rudnitskiy%2C+A+G">A. G. Rudnitskiy</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=Stanghellini%2C+C">C. Stanghellini</a>, <a href="/search/astro-ph?searchtype=author&query=de+Vicente%2C+P">P. de Vicente</a>, <a href="/search/astro-ph?searchtype=author&query=Voitsik%2C+P+A">P. A. Voitsik</a>, <a href="/search/astro-ph?searchtype=author&query=Wolak%2C+P">P. Wolak</a>, <a href="/search/astro-ph?searchtype=author&query=Zhekanis%2C+G+V">G. V. Zhekanis</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="1711.06713v1-abstract-short" style="display: inline;"> The high brightness temperatures, $T_\mathrm{b}\gtrsim 10^{13}$ K, detected in several active galactic nuclei by RadioAstron space VLBI observations challenge theoretical limits. Refractive scattering by the interstellar medium may affect such measurements. We quantify the scattering properties and the sub-mas scale source parameters for the quasar B0529+483. Using RadioAstron correlated flux dens… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1711.06713v1-abstract-full').style.display = 'inline'; document.getElementById('1711.06713v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1711.06713v1-abstract-full" style="display: none;"> The high brightness temperatures, $T_\mathrm{b}\gtrsim 10^{13}$ K, detected in several active galactic nuclei by RadioAstron space VLBI observations challenge theoretical limits. Refractive scattering by the interstellar medium may affect such measurements. We quantify the scattering properties and the sub-mas scale source parameters for the quasar B0529+483. Using RadioAstron correlated flux density measurements at 1.7, 4.8, and 22 GHz on projected baselines up to 240,000 km we find two characteristic angular scales in the quasar core, about 100 $渭$as and 10 $渭$as. Some indications of scattering substructure are found. Very high brightness temperatures, $T_\mathrm{b}\geq 10^{13}$ K, are estimated at 4.8 GHz and 22 GHz even taking into account the refractive scattering. Our findings suggest a clear dominance of the particle energy density over the magnetic field energy density in the core of this quasar. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1711.06713v1-abstract-full').style.display = 'none'; document.getElementById('1711.06713v1-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 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">14 pages, 9 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> MNRAS 474 (2018) 3523 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1710.10074">arXiv:1710.10074</a> <span> [<a href="https://arxiv.org/pdf/1710.10074">pdf</a>, <a href="https://arxiv.org/format/1710.10074">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="General Relativity and Quantum Cosmology">gr-qc</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/10.1016/j.physleta.2017.09.014">10.1016/j.physleta.2017.09.014 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Probing the gravitational redshift with an Earth-orbiting satellite </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Litvinov%2C+D+A">D. A. Litvinov</a>, <a href="/search/astro-ph?searchtype=author&query=Rudenko%2C+V+N">V. N. Rudenko</a>, <a href="/search/astro-ph?searchtype=author&query=Alakoz%2C+A+V">A. V. Alakoz</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Bartel%2C+N">N. Bartel</a>, <a href="/search/astro-ph?searchtype=author&query=Belonenko%2C+A+V">A. V. Belonenko</a>, <a href="/search/astro-ph?searchtype=author&query=Belousov%2C+K+G">K. G. Belousov</a>, <a href="/search/astro-ph?searchtype=author&query=Bietenholz%2C+M">M. Bietenholz</a>, <a href="/search/astro-ph?searchtype=author&query=Biriukov%2C+A+V">A. V. Biriukov</a>, <a href="/search/astro-ph?searchtype=author&query=Carman%2C+R">R. Carman</a>, <a href="/search/astro-ph?searchtype=author&query=Cim%C3%B3%2C+G">G. Cim贸</a>, <a href="/search/astro-ph?searchtype=author&query=Courde%2C+C">C. Courde</a>, <a href="/search/astro-ph?searchtype=author&query=Dirkx%2C+D">D. Dirkx</a>, <a href="/search/astro-ph?searchtype=author&query=Duev%2C+D+A">D. A. Duev</a>, <a href="/search/astro-ph?searchtype=author&query=Filetkin%2C+A+I">A. I. Filetkin</a>, <a href="/search/astro-ph?searchtype=author&query=Granato%2C+G">G. Granato</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=Gusev%2C+A+V">A. V. Gusev</a>, <a href="/search/astro-ph?searchtype=author&query=Haas%2C+R">R. Haas</a>, <a href="/search/astro-ph?searchtype=author&query=Herold%2C+G">G. Herold</a>, <a href="/search/astro-ph?searchtype=author&query=Kahlon%2C+A">A. Kahlon</a>, <a href="/search/astro-ph?searchtype=author&query=Kanevsky%2C+B+Z">B. Z. Kanevsky</a>, <a href="/search/astro-ph?searchtype=author&query=Kauts%2C+V+L">V. L. Kauts</a>, <a href="/search/astro-ph?searchtype=author&query=Kopelyansky%2C+G+D">G. D. Kopelyansky</a>, <a href="/search/astro-ph?searchtype=author&query=Kovalenko%2C+A+V">A. V. Kovalenko</a> , et al. (23 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="1710.10074v1-abstract-short" style="display: inline;"> We present an approach to testing the gravitational redshift effect using the RadioAstron satellite. The experiment is based on a modification of the Gravity Probe A scheme of nonrelativistic Doppler compensation and benefits from the highly eccentric orbit and ultra-stable atomic hydrogen maser frequency standard of the RadioAstron satellite. Using the presented techniques we expect to reach an a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1710.10074v1-abstract-full').style.display = 'inline'; document.getElementById('1710.10074v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1710.10074v1-abstract-full" style="display: none;"> We present an approach to testing the gravitational redshift effect using the RadioAstron satellite. The experiment is based on a modification of the Gravity Probe A scheme of nonrelativistic Doppler compensation and benefits from the highly eccentric orbit and ultra-stable atomic hydrogen maser frequency standard of the RadioAstron satellite. Using the presented techniques we expect to reach an accuracy of the gravitational redshift test of order $10^{-5}$, a magnitude better than that of Gravity Probe A. Data processing is ongoing, our preliminary results agree with the validity of the Einstein Equivalence Principle. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1710.10074v1-abstract-full').style.display = 'none'; document.getElementById('1710.10074v1-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 October, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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">Submitted to Physics Letters 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/1707.01386">arXiv:1707.01386</a> <span> [<a href="https://arxiv.org/pdf/1707.01386">pdf</a>, <a href="https://arxiv.org/format/1707.01386">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/10.1051/0004-6361/201731220">10.1051/0004-6361/201731220 <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 II. Observations of 3C 273 at minimum activity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Bruni%2C+G">G. Bruni</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=Casadio%2C+C">C. Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Lobanov%2C+A">A. Lobanov</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=Sokolovsky%2C+K+V">K. V. Sokolovsky</a>, <a href="/search/astro-ph?searchtype=author&query=Lisakov%2C+M+M">M. M. Lisakov</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A">A. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S">S. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Anderson%2C+J+M">J. M. Anderson</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=Savolainen%2C+T">T. Savolainen</a>, <a href="/search/astro-ph?searchtype=author&query=Vega-Garc%C3%ADa%2C+L">L. Vega-Garc铆a</a>, <a href="/search/astro-ph?searchtype=author&query=Fuentes%2C+A">A. Fuentes</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=Alberdi%2C+A">A. Alberdi</a>, <a href="/search/astro-ph?searchtype=author&query=Lee%2C+S+-">S. -S. Lee</a>, <a href="/search/astro-ph?searchtype=author&query=Lu%2C+R+-">R. -S. Lu</a>, <a href="/search/astro-ph?searchtype=author&query=P%C3%A9rez-Torres%2C+M">M. P茅rez-Torres</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">E. Ros</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="1707.01386v1-abstract-short" style="display: inline;"> RadioAstron is a 10 m orbiting radio telescope mounted on the Spektr-R satellite, launched in 2011, performing Space Very Long Baseline Interferometry (SVLBI) observations supported by a global ground array of radio telescopes. With an apogee of about 350 000 km, it is offering for the first time the possibility to perform 渭as-resolution imaging in the cm-band. We present observations at 22 GHz of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1707.01386v1-abstract-full').style.display = 'inline'; document.getElementById('1707.01386v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1707.01386v1-abstract-full" style="display: none;"> RadioAstron is a 10 m orbiting radio telescope mounted on the Spektr-R satellite, launched in 2011, performing Space Very Long Baseline Interferometry (SVLBI) observations supported by a global ground array of radio telescopes. With an apogee of about 350 000 km, it is offering for the first time the possibility to perform 渭as-resolution imaging in the cm-band. We present observations at 22 GHz of 3C 273, performed in 2014, designed to reach a maximum baseline of approximately nine Earth diameters. Reaching an angular resolution of 0.3 mas, we study a particularly low-activity state of the source, and estimate the nuclear region brightness temperature, comparing with the extreme one detected one year before during the RadioAstron early science period. We also make use of the VLBA-BU-BLAZAR survey data, at 43 GHz, to study the kinematics of the jet in a 1.5-year time window. We find that the nuclear brightness temperature is two orders of magnitude lower than the exceptionally high value detected in 2013 with RadioAstron at the same frequency (1.4x10^13 K, source-frame), and even one order of magnitude lower than the equipartition value. The kinematics analysis at 43 GHz shows that a new component was ejected 2 months after the 2013 epoch, visible also in our 22 GHz map presented here. Consequently this was located upstream of the core during the brightness temperature peak. These observations confirm that the previously detected extreme brightness temperature in 3C 273, exceeding the inverse Compton limit, is a short-lived phenomenon caused by a temporary departure from equipartition. Thus, the availability of interferometric baselines capable of providing 渭as angular resolution does not systematically imply measured brightness temperatures over the known physical limits for astrophysical sources. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1707.01386v1-abstract-full').style.display = 'none'; document.getElementById('1707.01386v1-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 July, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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 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 604, A111 (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1703.07651">arXiv:1703.07651</a> <span> [<a href="https://arxiv.org/pdf/1703.07651">pdf</a>, <a href="https://arxiv.org/format/1703.07651">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/10.1051/0004-6361/201630347">10.1051/0004-6361/201630347 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> First Multi-wavelength Campaign on the Gamma-ray-loud Active Galaxy IC 310 </p> <p class="authors"> <span class="search-hit">Authors:</span> <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=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=Biasuzzi%2C+B">B. Biasuzzi</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=Bonnefoy%2C+S">S. Bonnefoy</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">G. Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Borracci%2C+F">F. Borracci</a>, <a href="/search/astro-ph?searchtype=author&query=Bretz%2C+T">T. Bretz</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=Chatterjee%2C+A">A. Chatterjee</a>, <a href="/search/astro-ph?searchtype=author&query=Colin%2C+P">P. Colin</a>, <a href="/search/astro-ph?searchtype=author&query=Colombo%2C+E">E. Colombo</a> , et al. (138 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="1703.07651v1-abstract-short" style="display: inline;"> The extragalactic VHE gamma-ray sky is rich in blazars. These are jetted active galactic nuclei viewed at a small angle to the line-of-sight. Only a handful of objects viewed at a larger angle are known so far to emit above 100 GeV. Multi-wavelength studies of such objects up to the highest energies provide new insights into the particle and radiation processes of active galactic nuclei. We report… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.07651v1-abstract-full').style.display = 'inline'; document.getElementById('1703.07651v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1703.07651v1-abstract-full" style="display: none;"> The extragalactic VHE gamma-ray sky is rich in blazars. These are jetted active galactic nuclei viewed at a small angle to the line-of-sight. Only a handful of objects viewed at a larger angle are known so far to emit above 100 GeV. Multi-wavelength studies of such objects up to the highest energies provide new insights into the particle and radiation processes of active galactic nuclei. We report the results from the first multi-wavelength campaign observing the TeV detected nucleus of the active galaxy IC 310, whose jet is observed at a moderate viewing angle of 10 deg - 20 deg. The multi-instrument campaign was conducted between 2012 Nov. and 2013 Jan., and involved observations with MAGIC, Fermi, INTEGRAL, Swift, OVRO, MOJAVE and EVN. These observations were complemented with archival data from the AllWISE and 2MASS catalogs. A one-zone synchrotron self-Compton model was applied to describe the broad-band spectral energy distribution. IC 310 showed an extraordinary TeV flare at the beginning of the campaign, followed by a low, but still detectable TeV flux. Compared to previous measurements, the spectral shape was found to be steeper during the low emission state. Simultaneous observations in the soft X-ray band showed an enhanced energy flux state and a harder-when-brighter spectral shape behaviour. No strong correlated flux variability was found in other frequency regimes. The broad-band spectral energy distribution obtained from these observations supports the hypothesis of a double-hump structure. The harder-when-brighter trend in the X-ray and VHE emission is consistent with the behaviour expected from a synchrotron self-Compton scenario. The contemporaneous broad-band spectral energy distribution is well described with a one-zone synchrotron self-Compton model using parameters that are comparable to those found for other gamma-ray-emitting misaligned blazars. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.07651v1-abstract-full').style.display = 'none'; document.getElementById('1703.07651v1-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 March, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 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">15 pages, 10 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 603, A25 (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1607.00725">arXiv:1607.00725</a> <span> [<a href="https://arxiv.org/pdf/1607.00725">pdf</a>, <a href="https://arxiv.org/format/1607.00725">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/10.1051/0004-6361/201526727">10.1051/0004-6361/201526727 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Location of Gamma-ray emission and magnetic field strengths in OJ 287 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Hodgson%2C+J+A">J. A. Hodgson</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=Marscher%2C+A+P">A. P. Marscher</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=Rani%2C+B">B. Rani</a>, <a href="/search/astro-ph?searchtype=author&query=Marti-Vidal%2C+I">I. Marti-Vidal</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Sanchez%2C+S">S. Sanchez</a>, <a href="/search/astro-ph?searchtype=author&query=Bremer%2C+M">M. Bremer</a>, <a href="/search/astro-ph?searchtype=author&query=Lindqvist%2C+M">M. Lindqvist</a>, <a href="/search/astro-ph?searchtype=author&query=Uunila%2C+M">M. Uunila</a>, <a href="/search/astro-ph?searchtype=author&query=Kallunki%2C+J">J. Kallunki</a>, <a href="/search/astro-ph?searchtype=author&query=Vicente%2C+P">P. Vicente</a>, <a href="/search/astro-ph?searchtype=author&query=Fuhrmann%2C+L">L. Fuhrmann</a>, <a href="/search/astro-ph?searchtype=author&query=Angelakis%2C+E">E. Angelakis</a>, <a href="/search/astro-ph?searchtype=author&query=Karamanavis%2C+V">V. Karamanavis</a>, <a href="/search/astro-ph?searchtype=author&query=Myserlis%2C+I">I. Myserlis</a>, <a href="/search/astro-ph?searchtype=author&query=Nestoras%2C+I">I. Nestoras</a>, <a href="/search/astro-ph?searchtype=author&query=Chidiac%2C+C">C. Chidiac</a>, <a href="/search/astro-ph?searchtype=author&query=Sievers%2C+A">A. Sievers</a>, <a href="/search/astro-ph?searchtype=author&query=Gurwell%2C+M">M. Gurwell</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="1607.00725v1-abstract-short" style="display: inline;"> The Gamma-ray BL Lac object OJ 287 is known to exhibit inner-parsec "jet-wobbling", high degrees of variability at all wavelengths and quasi-stationary features including an apparent (~100 deg) position angle change in projection on the sky plane. Sub-50 micro-arcsecond resolution 86 GHz observations with the global mm-VLBI array (GMVA) supplement ongoing multi-frequency VLBI blazar monitoring at… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1607.00725v1-abstract-full').style.display = 'inline'; document.getElementById('1607.00725v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1607.00725v1-abstract-full" style="display: none;"> The Gamma-ray BL Lac object OJ 287 is known to exhibit inner-parsec "jet-wobbling", high degrees of variability at all wavelengths and quasi-stationary features including an apparent (~100 deg) position angle change in projection on the sky plane. Sub-50 micro-arcsecond resolution 86 GHz observations with the global mm-VLBI array (GMVA) supplement ongoing multi-frequency VLBI blazar monitoring at lower frequencies. Using these maps together with cm/mm total intensity and Gamma-ray observations from Fermi/LAT from 2008-2014, we aimed to determine the location of Gamma-ray emission and to explain the inner-mas structural changes. Observations with the GMVA offer approximately double the angular resolution compared with 43 GHz VLBA observations and allow us to observe above the synchrotron self-absorption peak frequency. The jet was spectrally decomposed at multiple locations along the jet. From this we derived estimates of the magnetic field. How the field decreases down the jet allowed an estimate of the distance to the jet apex and an estimate of the magnetic field strength at the jet apex and in the broad line region. Combined with accurate kinematics we attempt to locate the site of Gamma-ray activity, radio flares and spectral changes. Strong Gamma-ray flares appeared to originate from either the "core" region, a downstream stationary feature, or both, with Gamma-ray activity significantly correlated with radio flaring in the downstream quasi-stationary feature. Magnetic field estimates were determined at multiple locations along the jet, with the magnetic field found to be >1.6 G in the "core" and >0.4 G in the downstream quasi-stationary feature. We therefore found upper limits on the location of the "core" as >6.0 pc from the jet apex and determined an upper limit on the magnetic field near the jet base of the order of thousands of Gauss. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1607.00725v1-abstract-full').style.display = 'none'; document.getElementById('1607.00725v1-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, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2016. </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">30 pages, 20 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 597, A80 (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1605.05832">arXiv:1605.05832</a> <span> [<a href="https://arxiv.org/pdf/1605.05832">pdf</a>, <a href="https://arxiv.org/format/1605.05832">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="General Relativity and Quantum Cosmology">gr-qc</span> </div> </div> <p class="title is-5 mathjax"> RadioAstron gravitational redshift experiment: status update </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Litvinov%2C+D+A">D. A. Litvinov</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Bartel%2C+N">N. Bartel</a>, <a href="/search/astro-ph?searchtype=author&query=Belousov%2C+K+G">K. G. Belousov</a>, <a href="/search/astro-ph?searchtype=author&query=Bietenholz%2C+M">M. Bietenholz</a>, <a href="/search/astro-ph?searchtype=author&query=Biriukov%2C+A+V">A. V. Biriukov</a>, <a href="/search/astro-ph?searchtype=author&query=Cimo%2C+G">G. Cimo</a>, <a href="/search/astro-ph?searchtype=author&query=Duev%2C+D+A">D. A. Duev</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=Gusev%2C+A+V">A. V. Gusev</a>, <a href="/search/astro-ph?searchtype=author&query=Haas%2C+R">R. Haas</a>, <a href="/search/astro-ph?searchtype=author&query=Kauts%2C+V+L">V. L. Kauts</a>, <a href="/search/astro-ph?searchtype=author&query=Kanevsky%2C+B+Z">B. Z. Kanevsky</a>, <a href="/search/astro-ph?searchtype=author&query=Kovalenko%2C+A+V">A. V. Kovalenko</a>, <a href="/search/astro-ph?searchtype=author&query=Kronschnabl%2C+G">G. Kronschnabl</a>, <a href="/search/astro-ph?searchtype=author&query=Kulagin%2C+V+V">V. V. Kulagin</a>, <a href="/search/astro-ph?searchtype=author&query=Lindqvist%2C+M">M. Lindqvist</a>, <a href="/search/astro-ph?searchtype=author&query=Calves%2C+G+M">G. Molera Calves</a>, <a href="/search/astro-ph?searchtype=author&query=Neidhardt%2C+A">A. Neidhardt</a>, <a href="/search/astro-ph?searchtype=author&query=Ploetz%2C+C">C. Ploetz</a>, <a href="/search/astro-ph?searchtype=author&query=Pogrebenko%2C+S+V">S. V. Pogrebenko</a>, <a href="/search/astro-ph?searchtype=author&query=Porayko%2C+N+K">N. K. Porayko</a>, <a href="/search/astro-ph?searchtype=author&query=Rudenko%2C+V+N">V. N. Rudenko</a>, <a href="/search/astro-ph?searchtype=author&query=Smirnov%2C+A+I">A. I. Smirnov</a>, <a href="/search/astro-ph?searchtype=author&query=Sokolovsky%2C+K+V">K. V. Sokolovsky</a> , et al. (3 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="1605.05832v1-abstract-short" style="display: inline;"> A test of a cornerstone of general relativity, the gravitational redshift effect, is currently being conducted with the RadioAstron spacecraft, which is on a highly eccentric orbit around Earth. Using ground radio telescopes to record the spacecraft signal, synchronized to its ultra-stable on-board H-maser, we can probe the varying flow of time on board with unprecedented accuracy. The observation… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1605.05832v1-abstract-full').style.display = 'inline'; document.getElementById('1605.05832v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1605.05832v1-abstract-full" style="display: none;"> A test of a cornerstone of general relativity, the gravitational redshift effect, is currently being conducted with the RadioAstron spacecraft, which is on a highly eccentric orbit around Earth. Using ground radio telescopes to record the spacecraft signal, synchronized to its ultra-stable on-board H-maser, we can probe the varying flow of time on board with unprecedented accuracy. The observations performed so far, currently being analyzed, have already allowed us to measure the effect with a relative accuracy of $4\times10^{-4}$. We expect to reach $2.5\times10^{-5}$ with additional observations in 2016, an improvement of almost a magnitude over the 40-year old result of the GP-A mission. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1605.05832v1-abstract-full').style.display = 'none'; document.getElementById('1605.05832v1-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 May, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2016. </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">Submitted to the 14th Marcel Grossmann Meeting Proceedings</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1603.04221">arXiv:1603.04221</a> <span> [<a href="https://arxiv.org/pdf/1603.04221">pdf</a>, <a href="https://arxiv.org/format/1603.04221">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/10.1051/0004-6361/201628412">10.1051/0004-6361/201628412 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> First 3 mm-VLBI imaging of the two-sided jet in Cygnus A. Zooming into the launching region </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=Krichbaum%2C+T+P">T. P. Krichbaum</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Bremer%2C+M">M. Bremer</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="1603.04221v1-abstract-short" style="display: inline;"> We present for the first time Very-Long-Baseline Interferometry images of the radio galaxy Cygnus A at the frequency of $86$ $\rm GHz$. Thanks to the high spatial resolution of only ${\sim}200$ Schwarzschild radii ($R_{\bf S}$), such observations provide an extremely detailed view of the nuclear regions in this archetypal object and allow us to derive important constraints for theoretical models d… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1603.04221v1-abstract-full').style.display = 'inline'; document.getElementById('1603.04221v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1603.04221v1-abstract-full" style="display: none;"> We present for the first time Very-Long-Baseline Interferometry images of the radio galaxy Cygnus A at the frequency of $86$ $\rm GHz$. Thanks to the high spatial resolution of only ${\sim}200$ Schwarzschild radii ($R_{\bf S}$), such observations provide an extremely detailed view of the nuclear regions in this archetypal object and allow us to derive important constraints for theoretical models describing the launching of relativistic jets. A pixel-based analysis of the jet outflow, which still appears two-sided on the scales probed, was performed. By fitting Gaussian functions to the transverse intensity profiles, we could determine the jet width in the nuclear region. The base of the jets appears wide. The minimum measured transverse width of ${\sim} (227\pm98)$ $R_{\bf S}$ is significantly larger than the radius of the Innermost Stable Circular Orbit, suggesting that the outer accretion disk is contributing to the jet launching. The existence of a faster and Doppler de-boosted inner section, powered either from the rotation of the inner regions of the accretion disk or by the spinning black hole, is suggested by the kinematic properties and by the observed limb brightening of the flow. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1603.04221v1-abstract-full').style.display = 'none'; document.getElementById('1603.04221v1-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 March, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2016. </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">4 pages, 4 figures. Accepted for publication as a Letter 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 588, L9 (2016) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1601.05806">arXiv:1601.05806</a> <span> [<a href="https://arxiv.org/pdf/1601.05806">pdf</a>, <a href="https://arxiv.org/format/1601.05806">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/10.3847/2041-8205/820/1/L9">10.3847/2041-8205/820/1/L9 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> RadioAstron Observations of the Quasar 3C273: a Challenge to the Brightness Temperature Limit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kovalev%2C+Y+Y">Y. Y. Kovalev</a>, <a href="/search/astro-ph?searchtype=author&query=Kardashev%2C+N+S">N. S. Kardashev</a>, <a href="/search/astro-ph?searchtype=author&query=Kellermann%2C+K+I">K. I. Kellermann</a>, <a href="/search/astro-ph?searchtype=author&query=Lobanov%2C+A+P">A. P. Lobanov</a>, <a href="/search/astro-ph?searchtype=author&query=Johnson%2C+M+D">M. D. Johnson</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=Voitsik%2C+P+A">P. A. Voitsik</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=Anderson%2C+J+M">J. M. Anderson</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Jauncey%2C+D+L">D. L. Jauncey</a>, <a href="/search/astro-ph?searchtype=author&query=Ghigo%2C+F">F. Ghigo</a>, <a href="/search/astro-ph?searchtype=author&query=Ghosh%2C+T">T. Ghosh</a>, <a href="/search/astro-ph?searchtype=author&query=Kraus%2C+A">A. Kraus</a>, <a href="/search/astro-ph?searchtype=author&query=Kovalev%2C+Y+A">Yu. A. Kovalev</a>, <a href="/search/astro-ph?searchtype=author&query=Lisakov%2C+M+M">M. M. Lisakov</a>, <a href="/search/astro-ph?searchtype=author&query=Petrov%2C+L+Y">L. Yu. Petrov</a>, <a href="/search/astro-ph?searchtype=author&query=Romney%2C+J+D">J. D. Romney</a>, <a href="/search/astro-ph?searchtype=author&query=Salter%2C+C+J">C. J. Salter</a>, <a href="/search/astro-ph?searchtype=author&query=Sokolovsky%2C+K+V">K. V. Sokolovsky</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="1601.05806v2-abstract-short" style="display: inline;"> Inverse Compton cooling limits the brightness temperature of the radiating plasma to a maximum of $10^{11.5}$ K. Relativistic boosting can increase its observed value, but apparent brightness temperatures much in excess of $10^{13}$ K are inaccessible using ground-based very long baseline interferometry (VLBI) at any wavelength. We present observations of the quasar 3C273, made with the space VLBI… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1601.05806v2-abstract-full').style.display = 'inline'; document.getElementById('1601.05806v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1601.05806v2-abstract-full" style="display: none;"> Inverse Compton cooling limits the brightness temperature of the radiating plasma to a maximum of $10^{11.5}$ K. Relativistic boosting can increase its observed value, but apparent brightness temperatures much in excess of $10^{13}$ K are inaccessible using ground-based very long baseline interferometry (VLBI) at any wavelength. We present observations of the quasar 3C273, made with the space VLBI mission RadioAstron on baselines up to 171,000 km, which directly reveal the presence of angular structure as small as 26 $渭$as (2.7 light months) and brightness temperature in excess of $10^{13}$ K. These measurements challenge our understanding of the non-thermal continuum emission in the vicinity of supermassive black holes and require a much higher Doppler factor than what is determined from jet apparent kinematics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1601.05806v2-abstract-full').style.display = 'none'; document.getElementById('1601.05806v2-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 March, 2016; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 21 January, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2016. </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, 2 figures, 1 table; accepted by the Astrophysical Journal Letters</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Astrophysical Journal Letters 820 (2016) L9 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1512.04690">arXiv:1512.04690</a> <span> [<a href="https://arxiv.org/pdf/1512.04690">pdf</a>, <a href="https://arxiv.org/format/1512.04690">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/10.3847/0004-637X/817/2/96">10.3847/0004-637X/817/2/96 <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. I. Imaging BL Lacertae at 21 microarcsecond resolution </p> <p class="authors"> <span class="search-hit">Authors:</span> <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=Lobanov%2C+A+P">Andrei P. Lobanov</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=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=Mizuno%2C+Y">Yosuke Mizuno</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">Uwe Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Sokolovsky%2C+K+V">Kirill V. Sokolovsky</a>, <a href="/search/astro-ph?searchtype=author&query=Anderson%2C+J+M">James M. Anderson</a>, <a href="/search/astro-ph?searchtype=author&query=Galindo%2C+P">Pablo Galindo</a>, <a href="/search/astro-ph?searchtype=author&query=Kardashev%2C+N+S">Nikolay S. Kardashev</a>, <a href="/search/astro-ph?searchtype=author&query=Lisakov%2C+M+M">Mikhail M. Lisakov</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="1512.04690v1-abstract-short" style="display: inline;"> We present the first polarimetric space VLBI imaging observations at 22 GHz. BL Lacertae was observed in 2013 November 10 with the RadioAstron space VLBI mission, including a ground array of 15 radio telescopes. The instrumental polarization of the space radio telescope is found to be within 9%, demonstrating the polarimetric imaging capabilities of RadioAstron at 22 GHz. Ground-space fringes were… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1512.04690v1-abstract-full').style.display = 'inline'; document.getElementById('1512.04690v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1512.04690v1-abstract-full" style="display: none;"> We present the first polarimetric space VLBI imaging observations at 22 GHz. BL Lacertae was observed in 2013 November 10 with the RadioAstron space VLBI mission, including a ground array of 15 radio telescopes. The instrumental polarization of the space radio telescope is found to be within 9%, demonstrating the polarimetric imaging capabilities of RadioAstron at 22 GHz. Ground-space fringes were obtained up to a projected baseline distance of 7.9 Earth's diameters in length, allowing us to image the jet in BL Lacertae with a maximum angular resolution of 21 $渭$as, the highest achieved to date. We find evidence for emission upstream of the radio core, which may correspond to a recollimation shock at about 40 $渭$as from the jet apex, in a pattern that includes other recollimation shocks at approximately 100 $渭$as and 250 $渭$as from the jet apex. Polarized emission is detected in two components within the innermost 0.5 mas from the core, as well as in some knots 3 mas downstream. Faraday rotation analysis, obtained from combining RadioAstron 22 GHz and ground-based 15 GHz and 43 GHz images, shows a gradient in rotation measure and Faraday corrected polarization vector as a function of position angle with respect to the core, suggesting that the jet in BL Lacertae is threaded by a helical magnetic field. The intrinsic de-boosted brightness temperature in the unresolved core exceeds $3\!\times\!10^{12}$ K, suggesting at the very least departure from equipartition of energy between the magnetic field and radiating particles. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1512.04690v1-abstract-full').style.display = 'none'; document.getElementById('1512.04690v1-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 December, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2015. </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> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> The Astrophysical journal 817 (2016) 96 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1509.06250">arXiv:1509.06250</a> <span> [<a href="https://arxiv.org/pdf/1509.06250">pdf</a>, <a href="https://arxiv.org/format/1509.06250">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/10.1051/0004-6361/201526985">10.1051/0004-6361/201526985 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> The stratified two-sided jet of Cygnus A. Acceleration and collimation </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=Krichbaum%2C+T+P">T. P. Krichbaum</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Mertens%2C+F">F. Mertens</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">E. Ros</a>, <a href="/search/astro-ph?searchtype=author&query=Alef%2C+W">W. Alef</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="1509.06250v1-abstract-short" style="display: inline;"> High-resolution Very-Long-Baseline Interferometry observations of relativistic jets are essential to constrain fundamental parameters of jet formation models. At a distance of 249 Mpc, Cygnus A is a unique target for such studies, being the only Fanaroff-Riley Class II radio galaxy for which a detailed sub-parsec scale imaging of the base of both jet and counter-jet can be obtained. Observing at m… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1509.06250v1-abstract-full').style.display = 'inline'; document.getElementById('1509.06250v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1509.06250v1-abstract-full" style="display: none;"> High-resolution Very-Long-Baseline Interferometry observations of relativistic jets are essential to constrain fundamental parameters of jet formation models. At a distance of 249 Mpc, Cygnus A is a unique target for such studies, being the only Fanaroff-Riley Class II radio galaxy for which a detailed sub-parsec scale imaging of the base of both jet and counter-jet can be obtained. Observing at millimeter wavelengths unveils those regions which appear self-absorbed at longer wavelengths and enables an extremely sharp view towards the nucleus to be obtained. We performed 7 mm Global VLBI observations, achieving ultra-high resolution imaging on scales down to 90 $渭$as. This resolution corresponds to a linear scale of only ${\sim}$400 Schwarzschild radii (for $M_{\mathrm{BH}}=2.5 \times 10^9 M_{\odot}$). We studied the kinematic properties of the main emission features of the two-sided flow and probed its transverse structure through a pixel-based analysis. We suggest that a fast and a slow layer, with different acceleration gradients, exist in the flow. The extension of the acceleration region is large (${\sim} 10^4 R_{\mathrm{S}}$), indicating that the jet is magnetically-driven. The limb brightening of both jet and counter-jet and their large opening angles ($蠁_\mathrm{J}{\sim} 10^{\circ}$) strongly favor a spine-sheath structure. In the acceleration zone, the flow has a parabolic shape ($r\propto z^{0.55\pm 0.07}$). The acceleration gradients and the collimation profile are consistent with the expectations for a jet in "equilibrium'' (Lyubarsky 2009), achieved in the presence of a mild gradient of the external pressure ($p\propto z^{-k}, k\leq2$).} <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1509.06250v1-abstract-full').style.display = 'none'; document.getElementById('1509.06250v1-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 September, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2015. </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">9 pages, 8 figures. Accepted for publication in 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 585, A33 (2016) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1508.05031">arXiv:1508.05031</a> <span> [<a href="https://arxiv.org/pdf/1508.05031">pdf</a>, <a href="https://arxiv.org/ps/1508.05031">ps</a>, <a href="https://arxiv.org/format/1508.05031">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"> Black Hole Lightning from the Peculiar Gamma-Ray Loud Active Galactic Nucleus IC 310 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Glawion%2C+D+E">Dorit Eisenacher Glawion</a>, <a href="/search/astro-ph?searchtype=author&query=Sitarek%2C+J">Julian Sitarek</a>, <a href="/search/astro-ph?searchtype=author&query=Mannheim%2C+K">Karl Mannheim</a>, <a href="/search/astro-ph?searchtype=author&query=Colin%2C+P">Pierre Colin</a>, <a href="/search/astro-ph?searchtype=author&query=Kadler%2C+M">Matthias Kadler</a>, <a href="/search/astro-ph?searchtype=author&query=Schulz%2C+R">Robert Schulz</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">Eduardo Ros</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">Uwe Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Krau%C3%9F%2C+F">Felicia Krau脽</a>, <a href="/search/astro-ph?searchtype=author&query=Wilms%2C+J">J枚rn 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="1508.05031v1-abstract-short" style="display: inline;"> The nearby active galaxy IC 310, located in the outskirts of the Perseus cluster of galaxies is a bright and variable multi-wavelength emitter from the radio regime up to very high gamma-ray energies above 100 GeV. Originally, the nucleus of IC 310 has been classified as a radio galaxy. However, studies of the multi-wavelength emission showed several properties similarly to those found from blazar… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1508.05031v1-abstract-full').style.display = 'inline'; document.getElementById('1508.05031v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1508.05031v1-abstract-full" style="display: none;"> The nearby active galaxy IC 310, located in the outskirts of the Perseus cluster of galaxies is a bright and variable multi-wavelength emitter from the radio regime up to very high gamma-ray energies above 100 GeV. Originally, the nucleus of IC 310 has been classified as a radio galaxy. However, studies of the multi-wavelength emission showed several properties similarly to those found from blazars as well as radio galaxies. In late 2012, we have organized the first contemporaneous multi-wavelength campaign including radio, optical, X-ray and gamma-ray instruments. During this campaign an exceptionally bright flare of IC 310 was detected with the MAGIC telescopes in November 2012 reaching an averaged flux level in the night of up to one Crab above 1 TeV with a hard spectrum over two decades in energy. The intra-night light curve showed a series of strong outbursts with flux-doubling time scales as fast as a few minutes. The fast variability constrains the size of the gamma-ray emission regime to be smaller than 20% of the gravitational radius of its central black hole. This challenges the shock acceleration models, commonly used to explain gamma-ray radiation from active galaxies. Here, we will present more details on the MAGIC data and discuss several possible alternative emission models. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1508.05031v1-abstract-full').style.display = 'none'; document.getElementById('1508.05031v1-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 August, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2015. </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, 5 figures, Proceedings of the 34th International Cosmic Ray Conference, 30 July - 6 August, 2015, The Hague, The Netherlands</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1504.04273">arXiv:1504.04273</a> <span> [<a href="https://arxiv.org/pdf/1504.04273">pdf</a>, <a href="https://arxiv.org/format/1504.04273">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="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/10.1051/0004-6361/201526335">10.1051/0004-6361/201526335 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> RadioAstron space VLBI imaging of polarized radio emission in the high-redshift quasar 0642+449 at 1.6 GHz </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Lobanov%2C+A+P">A. P. Lobanov</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=Bruni%2C+G">G. Bruni</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=Anderson%2C+J">J. Anderson</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Kraus%2C+A">A. Kraus</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=Lisakov%2C+M+M">M. M. Lisakov</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=Voytsik%2C+P+A">P. A. Voytsik</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="1504.04273v2-abstract-short" style="display: inline;"> Polarization of radio emission in extragalactic jets at a sub-milliarcsecond angular resolution holds important clues for understanding the structure of the magnetic field in the inner regions of the jets and in close vicinity of the supermassive black holes in the centers of active galaxies. Space VLBI observations provide a unique tool for polarimetric imaging at a sub-milliarcsecond angular res… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1504.04273v2-abstract-full').style.display = 'inline'; document.getElementById('1504.04273v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1504.04273v2-abstract-full" style="display: none;"> Polarization of radio emission in extragalactic jets at a sub-milliarcsecond angular resolution holds important clues for understanding the structure of the magnetic field in the inner regions of the jets and in close vicinity of the supermassive black holes in the centers of active galaxies. Space VLBI observations provide a unique tool for polarimetric imaging at a sub-milliarcsecond angular resolution and studying the properties of magnetic field in active galactic nuclei on scales of less than 10^4 gravitational radii. A space VLBI observation of high-redshift quasar TXS 0642+449 (OH 471), made at a wavelength of 18 cm (frequency of 1.6 GHz) as part of the Early Science Programme (ESP) of the RadioAstron} mission, is used here to test the polarimetric performance of the orbiting Space Radio Telescope (SRT) employed by the mission, to establish a methodology for making full Stokes polarimetry with space VLBI at 1.6 GHz, and to study the polarized emission in the target object on sub-milliarcsecond scales. Polarization leakage of the SRT at 18 cm is found to be within 9 percents in amplitude, demonstrating the feasibility of high fidelity polarization imaging with RadioAstron at this wavelength. A polarimetric image of 0642+449 with a resolution of 0.8 mas (signifying an ~4 times improvement over ground VLBI observations at the same wavelength) is obtained. The image shows a compact core-jet structure with low (~2%) polarization and predominantly transverse magnetic field in the nuclear region. The VLBI data also uncover a complex structure of the nuclear region, with two prominent features possibly corresponding to the jet base and a strong recollimation shock. The maximum brightness temperature at the jet base can be as high as 4*10^13 K. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1504.04273v2-abstract-full').style.display = 'none'; document.getElementById('1504.04273v2-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> 8 July, 2015; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 16 April, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2015. </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, 10 pages, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Astronomy and Astrophysics 583 (2015) A100 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1504.01272">arXiv:1504.01272</a> <span> [<a href="https://arxiv.org/pdf/1504.01272">pdf</a>, <a href="https://arxiv.org/format/1504.01272">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"> High resolution mm-VLBI imaging of Cygnus A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Boccardi%2C+B">Bia Boccardi</a>, <a href="/search/astro-ph?searchtype=author&query=Krichbaum%2C+T">Thomas Krichbaum</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">Uwe Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">Eduardo Ros</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="1504.01272v1-abstract-short" style="display: inline;"> At a distance of 249 Mpc ($z$=0.056), Cygnus A is the only powerful FR II radio galaxy for which a detailed sub-parsec scale imaging of the base of both jet and counter-jet can be obtained. Observing with VLBI at millimeter wavelengths is fundamental for this object, as it uncovers those regions which appear self-absorbed or free-free absorbed by a circumnuclear torus at longer wavelengths. We per… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1504.01272v1-abstract-full').style.display = 'inline'; document.getElementById('1504.01272v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1504.01272v1-abstract-full" style="display: none;"> At a distance of 249 Mpc ($z$=0.056), Cygnus A is the only powerful FR II radio galaxy for which a detailed sub-parsec scale imaging of the base of both jet and counter-jet can be obtained. Observing with VLBI at millimeter wavelengths is fundamental for this object, as it uncovers those regions which appear self-absorbed or free-free absorbed by a circumnuclear torus at longer wavelengths. We performed 7 mm Global VLBI observations, achieving ultra-high resolution imaging on scales down to 90 $渭$as. This resolution corresponds to a linear scale of only $\sim$400 Schwarzschild radii. We studied the transverse structure of the jets through a pixel-based analysis, and kinematic properties of the main emission features by modeling the interferometric visibilities with two-dimensional Gaussian components. Both jets appear limb-brightened, and their opening angles are relatively large ($蠁_\mathrm {j}\sim 10^{\circ}$). The flow is observed to accelerate within the inner-jet up to scales of $\sim$1 pc, while lower speeds and uniform motions are measured further downstream. A single component seen in the counter-jet appears to be stationary. These observational properties are explained assuming the existence of transverse gradient of the bulk Lorentz factor across the jet, consisting of a fast central spine surrounded by a slower boundary layer. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1504.01272v1-abstract-full').style.display = 'none'; document.getElementById('1504.01272v1-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 April, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2015. </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, proceeding of the 12th European VLBI Network Symposium and Users Meeting - EVN 2014, 7-10 October 2014, Cagliari, Italy</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1502.03559">arXiv:1502.03559</a> <span> [<a href="https://arxiv.org/pdf/1502.03559">pdf</a>, <a href="https://arxiv.org/format/1502.03559">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"> The EVN view of the highly variable TeV active galaxy IC 310 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Schulz%2C+R">R. Schulz</a>, <a href="/search/astro-ph?searchtype=author&query=Kadler%2C+M">M. Kadler</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">E. Ros</a>, <a href="/search/astro-ph?searchtype=author&query=Glawion%2C+D+E">D. Eisenacher Glawion</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</a>, <a href="/search/astro-ph?searchtype=author&query=Els%C3%A4sser%2C+D">D. Els盲sser</a>, <a href="/search/astro-ph?searchtype=author&query=Grossberger%2C+C">C. Grossberger</a>, <a href="/search/astro-ph?searchtype=author&query=Kreykenbohm%2C+I">I. Kreykenbohm</a>, <a href="/search/astro-ph?searchtype=author&query=Mannheim%2C+K">K. Mannheim</a>, <a href="/search/astro-ph?searchtype=author&query=M%C3%BCller%2C+C">C. M眉ller</a>, <a href="/search/astro-ph?searchtype=author&query=Tr%C3%BCstedt%2C+J">J. Tr眉stedt</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="1502.03559v1-abstract-short" style="display: inline;"> Very-high-energy $纬$-ray observations of the active galaxy IC 310 with the MAGIC telescopes have revealed fast variability with doubling time scales of less than 4.8min. This implies that the emission region in IC 310 is smaller than 20% of the gravitational radius of the central supermassive black hole with a mass of $3\times 10^8 M_\odot$, which poses serious questions on the emission mechanism… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1502.03559v1-abstract-full').style.display = 'inline'; document.getElementById('1502.03559v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1502.03559v1-abstract-full" style="display: none;"> Very-high-energy $纬$-ray observations of the active galaxy IC 310 with the MAGIC telescopes have revealed fast variability with doubling time scales of less than 4.8min. This implies that the emission region in IC 310 is smaller than 20% of the gravitational radius of the central supermassive black hole with a mass of $3\times 10^8 M_\odot$, which poses serious questions on the emission mechanism and classification of this enigmatic object. We report on the first quasi-simultaneous multi-frequency VLBI observations of IC 310 conducted with the EVN. We find a blazar-like one-sided core-jet structure on parsec scales, constraining the inclination angle to be less than $\sim 20^\circ$ but very small angles are excluded to limit the de-projected length of the large-scale radio jet. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1502.03559v1-abstract-full').style.display = 'none'; document.getElementById('1502.03559v1-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 February, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2015. </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">4 pages, proceedings of the 12th European VLBI Network Symposium and Users Meeting - EVN 2014, 7-10 October 2014, Cagliari, Italy. Published online in PoS, ID.109</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1502.01126">arXiv:1502.01126</a> <span> [<a href="https://arxiv.org/pdf/1502.01126">pdf</a>, <a href="https://arxiv.org/ps/1502.01126">ps</a>, <a href="https://arxiv.org/format/1502.01126">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 particle acceleration of a peculiar gamma -ray radio galaxy IC 310 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Sitarek%2C+J">J. Sitarek</a>, <a href="/search/astro-ph?searchtype=author&query=Glawion%2C+D+E">D. Eisenacher Glawion</a>, <a href="/search/astro-ph?searchtype=author&query=Mannheim%2C+K">K. Mannheim</a>, <a href="/search/astro-ph?searchtype=author&query=Colin%2C+P">P. Colin</a>, <a href="/search/astro-ph?searchtype=author&query=Kadler%2C+M">M. Kadler</a>, <a href="/search/astro-ph?searchtype=author&query=Schultz%2C+R">R. Schultz</a>, <a href="/search/astro-ph?searchtype=author&query=Krau%C3%9F%2C+F">F. Krau脽</a>, <a href="/search/astro-ph?searchtype=author&query=Ros%2C+E">E. Ros</a>, <a href="/search/astro-ph?searchtype=author&query=Bach%2C+U">U. Bach</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="1502.01126v1-abstract-short" style="display: inline;"> IC 310 has recently been identified as a gamma-ray emitter based on observations at GeV energies with Fermi-LAT and at very high energies (VHE, E > 100 GeV) with the MAGIC telescopes. Despite IC 310 having been classified as a radio galaxy with the jet observed at an angle > 10 degrees, it exhibits a mixture of multiwavelength properties of a radio galaxy and a blazar, possibly making it a transit… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1502.01126v1-abstract-full').style.display = 'inline'; document.getElementById('1502.01126v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1502.01126v1-abstract-full" style="display: none;"> IC 310 has recently been identified as a gamma-ray emitter based on observations at GeV energies with Fermi-LAT and at very high energies (VHE, E > 100 GeV) with the MAGIC telescopes. Despite IC 310 having been classified as a radio galaxy with the jet observed at an angle > 10 degrees, it exhibits a mixture of multiwavelength properties of a radio galaxy and a blazar, possibly making it a transitional object. On the night of 12/13th of November 2012 the MAGIC telescopes observed a series of violent outbursts from the direction of IC 310 with flux-doubling time scales faster than 5 min and a peculiar spectrum spreading over 2 orders of magnitude. Such fast variability constrains the size of the emission region to be smaller than 20% of the gravitational radius of its central black hole, challenging the shock acceleration models, commonly used in explanation of gamma-ray radiation from active galaxies. Here we will show that this emission can be associated with pulsar-like particle acceleration by the electric field across a magnetospheric gap at the base of the jet. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1502.01126v1-abstract-full').style.display = 'none'; document.getElementById('1502.01126v1-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> 4 February, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2015. </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">2014 Fermi Symposium proceedings - eConf C14102.1</span> </p> </li> </ol> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous 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