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<button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <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/2411.16868">arXiv:2411.16868</a> <span> [<a href="https://arxiv.org/pdf/2411.16868">pdf</a>, <a href="https://arxiv.org/format/2411.16868">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> IXPE Observation of the Low-Synchrotron Peaked Blazar S4 0954+65 During An Optical-X-ray Flare </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kouch%2C+P+M">Pouya M. Kouch</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Fenu%2C+F">Francesco Fenu</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+H">Haocheng Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Boula%2C+S">Stella Boula</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Paraschos%2C+G+F">Georgios F. Paraschos</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Lindfors%2C+E">Elina Lindfors</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=Krawczynski%2C+H">Henric Krawczynski</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Hu%2C+K">Kun Hu</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Cavazzuti%2C+E">Elisabetta Cavazzuti</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D">Dmitry Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Gourni%2C+A">Anastasia Gourni</a>, <a href="/search/astro-ph?searchtype=author&query=Kiehlmann%2C+S">Sebastian Kiehlmann</a>, <a href="/search/astro-ph?searchtype=author&query=Kourtidis%2C+A">Angelos Kourtidis</a>, <a href="/search/astro-ph?searchtype=author&query=Mandarakas%2C+N">Nikos Mandarakas</a>, <a href="/search/astro-ph?searchtype=author&query=Triantafyllou%2C+N">Nikolaos Triantafyllou</a>, <a href="/search/astro-ph?searchtype=author&query=Vervelaki%2C+A">Anna Vervelaki</a> , et al. (112 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="2411.16868v1-abstract-short" style="display: inline;"> The X-ray polarization observations made possible with the Imaging X-ray Polarimetry Explorer (IXPE) offer new ways of probing high-energy emission processes in astrophysical jets from blazars. Here we report on the first X-ray polarization observation of the blazar S4 0954+65 in a high optical and X-ray state. During our multi-wavelength campaign on the source, we detected an optical flare whose… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.16868v1-abstract-full').style.display = 'inline'; document.getElementById('2411.16868v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.16868v1-abstract-full" style="display: none;"> The X-ray polarization observations made possible with the Imaging X-ray Polarimetry Explorer (IXPE) offer new ways of probing high-energy emission processes in astrophysical jets from blazars. Here we report on the first X-ray polarization observation of the blazar S4 0954+65 in a high optical and X-ray state. During our multi-wavelength campaign on the source, we detected an optical flare whose peak coincided with the peak of an X-ray flare. This optical-X-ray flare most likely took place in a feature moving along the parsec-scale jet, imaged at 43 GHz by the Very Long Baseline Array. The 43 GHz polarization angle of the moving component underwent a rotation near the time of the flare. In the optical band, prior to the IXPE observation, we measured the polarization angle to be aligned with the jet axis. In contrast, during the optical flare the optical polarization angle was perpendicular to the jet axis; after the flare, it reverted to being parallel to the jet axis. Due to the smooth behavior of the optical polarization angle during the flare, we favor shocks as the main acceleration mechanism. We also infer that the ambient magnetic field lines in the jet were parallel to the jet position angle. The average degree of optical polarization during the IXPE observation was (14.3$\pm$4.1)%. Despite the flare, we only detected an upper limit of 14% (at 3$蟽$ level) on the X-ray polarization degree; although a reasonable assumption on the X-ray polarization angle results in an upper limit of 8.8% ($3蟽$). We model the spectral energy distribution (SED) and spectral polarization distribution (SPD) of S4 0954+65 with leptonic (synchrotron self-Compton) and hadronic (proton and pair synchrotron) models. The constraints we obtain with our combined multi-wavelength polarization observations and SED modeling tentatively disfavor hadronic models for the X-ray emission in S4 0954+65. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.16868v1-abstract-full').style.display = 'none'; document.getElementById('2411.16868v1-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 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">Submitted to A&A, 16 pages, 5 figures, and 7 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.23140">arXiv:2410.23140</a> <span> [<a href="https://arxiv.org/pdf/2410.23140">pdf</a>, <a href="https://arxiv.org/format/2410.23140">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 from the first flaring activity of a high-synchrotron-peaked blazar with X-ray polarization and VHE gamma rays </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Abe%2C+K">K. Abe</a>, <a href="/search/astro-ph?searchtype=author&query=Abe%2C+S">S. Abe</a>, <a href="/search/astro-ph?searchtype=author&query=Abhir%2C+J">J. Abhir</a>, <a href="/search/astro-ph?searchtype=author&query=Abhishek%2C+A">A. Abhishek</a>, <a href="/search/astro-ph?searchtype=author&query=Acciari%2C+V+A">V. A. Acciari</a>, <a href="/search/astro-ph?searchtype=author&query=Aguasca-Cabot%2C+A">A. Aguasca-Cabot</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">I. Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Aniello%2C+T">T. Aniello</a>, <a href="/search/astro-ph?searchtype=author&query=Ansoldi%2C+S">S. Ansoldi</a>, <a href="/search/astro-ph?searchtype=author&query=Antonelli%2C+L+A">L. A. Antonelli</a>, <a href="/search/astro-ph?searchtype=author&query=Engels%2C+A+A">A. Arbet Engels</a>, <a href="/search/astro-ph?searchtype=author&query=Arcaro%2C+C">C. Arcaro</a>, <a href="/search/astro-ph?searchtype=author&query=Asano%2C+K">K. Asano</a>, <a href="/search/astro-ph?searchtype=author&query=Babi%C4%87%2C+A">A. Babi膰</a>, <a href="/search/astro-ph?searchtype=author&query=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=Barrios-Jim%C3%A9nez%2C+L">L. Barrios-Jim茅nez</a>, <a href="/search/astro-ph?searchtype=author&query=Batkovi%C4%87%2C+I">I. Batkovi膰</a>, <a href="/search/astro-ph?searchtype=author&query=Baxter%2C+J">J. Baxter</a>, <a href="/search/astro-ph?searchtype=author&query=Gonz%C3%A1lez%2C+J+B">J. Becerra Gonz谩lez</a>, <a href="/search/astro-ph?searchtype=author&query=Bednarek%2C+W">W. Bednarek</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardini%2C+E">E. Bernardini</a>, <a href="/search/astro-ph?searchtype=author&query=Bernete%2C+J">J. Bernete</a>, <a href="/search/astro-ph?searchtype=author&query=Berti%2C+A">A. Berti</a>, <a href="/search/astro-ph?searchtype=author&query=Besenrieder%2C+J">J. Besenrieder</a> , et al. (228 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="2410.23140v1-abstract-short" style="display: inline;"> We study a flaring activity of the HSP Mrk421 that was characterized from radio to very-high-energy (VHE; E $>0.1$TeV) gamma rays with MAGIC, Fermi-LAT, Swift, XMM-Newton and several optical and radio telescopes. These observations included, for the first time for a gamma-ray flare of a blazar, simultaneous X-ray polarization measurements with IXPE. We find substantial variability in both X-rays a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.23140v1-abstract-full').style.display = 'inline'; document.getElementById('2410.23140v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.23140v1-abstract-full" style="display: none;"> We study a flaring activity of the HSP Mrk421 that was characterized from radio to very-high-energy (VHE; E $>0.1$TeV) gamma rays with MAGIC, Fermi-LAT, Swift, XMM-Newton and several optical and radio telescopes. These observations included, for the first time for a gamma-ray flare of a blazar, simultaneous X-ray polarization measurements with IXPE. We find substantial variability in both X-rays and VHE gamma rays throughout the campaign, with the highest VHE flux above 0.2 TeV occurring during the IXPE observing window, and exceeding twice the flux of the Crab Nebula. However, the VHE and X-ray spectra are on average softer, and the correlation between these two bands weaker that those reported in previous flares of Mrk421. IXPE reveals an X-ray polarization degree significantly higher than that at radio and optical frequencies. The X-ray polarization angle varies by $\sim$100$^\circ$ on timescales of days, and the polarization degree changes by more than a factor 4. The highest X-ray polarization degree reaches 26%, around which a X-ray counter-clockwise hysteresis loop is measured with XMM-Newton. It suggests that the X-ray emission comes from particles close to the high-energy cutoff, hence possibly probing an extreme case of the Turbulent Extreme Multi-Zone model. We model the broadband emission with a simplified stratified jet model throughout the flare. The polarization measurements imply an electron distribution in the X-ray emitting region with a very high minimum Lorentz factor, which is expected in electron-ion plasma, as well as a variation of the emitting region size up to a factor of three during the flaring activity. We find no correlation between the fluxes and the evolution of the model parameters, which indicates a stochastic nature of the underlying physical mechanism. Such behaviour would be expected in a highly turbulent electron-ion plasma crossing a shock front. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.23140v1-abstract-full').style.display = 'none'; document.getElementById('2410.23140v1-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 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">Submitted to Astronomy and Astrophysics. Corresponding authors: Axel Arbet-Engels, Lea Heckmann, David Paneque</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.20582">arXiv:2410.20582</a> <span> [<a href="https://arxiv.org/pdf/2410.20582">pdf</a>, <a href="https://arxiv.org/format/2410.20582">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"> Evidence for a shock-compressed magnetic field in the northwestern rim of Vela Jr. from X-ray polarimetry </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Prokhorov%2C+D+A">Dmitry A. Prokhorov</a>, <a href="/search/astro-ph?searchtype=author&query=Yang%2C+Y">Yi-Jung Yang</a>, <a href="/search/astro-ph?searchtype=author&query=Ferrazzoli%2C+R">Riccardo Ferrazzoli</a>, <a href="/search/astro-ph?searchtype=author&query=Vink%2C+J">Jacco Vink</a>, <a href="/search/astro-ph?searchtype=author&query=Slane%2C+P">Patrick Slane</a>, <a href="/search/astro-ph?searchtype=author&query=Costa%2C+E">Enrico Costa</a>, <a href="/search/astro-ph?searchtype=author&query=Silvestri%2C+S">Stefano Silvestri</a>, <a href="/search/astro-ph?searchtype=author&query=Zhou%2C+P">Ping Zhou</a>, <a href="/search/astro-ph?searchtype=author&query=Bucciantini%2C+N">Niccol貌 Bucciantini</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Weisskopf%2C+M+C">Martin C. Weisskopf</a>, <a href="/search/astro-ph?searchtype=author&query=Baldini%2C+L">Luca Baldini</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">Victor Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Ehlert%2C+S+R">Steven R. Ehlert</a>, <a href="/search/astro-ph?searchtype=author&query=Heyl%2C+J">Jeremy Heyl</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">Philip Kaaret</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Marin%2C+F">Fr茅d茅ric Marin</a>, <a href="/search/astro-ph?searchtype=author&query=Mizuno%2C+T">Tsunefumi Mizuno</a>, <a href="/search/astro-ph?searchtype=author&query=Ng%2C+C">Chi-Yung Ng</a>, <a href="/search/astro-ph?searchtype=author&query=Pesce-Rollins%2C+M">Melissa Pesce-Rollins</a>, <a href="/search/astro-ph?searchtype=author&query=Sgr%C3%B2%2C+C">Carmelo Sgr貌</a>, <a href="/search/astro-ph?searchtype=author&query=Soffitta%2C+P">Paolo Soffitta</a>, <a href="/search/astro-ph?searchtype=author&query=Swartz%2C+D+A">Douglas A. Swartz</a>, <a href="/search/astro-ph?searchtype=author&query=Tamagawa%2C+T">Toru Tamagawa</a> , et al. (75 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="2410.20582v1-abstract-short" style="display: inline;"> Synchrotron X-ray emission has been detected from nearly a dozen young supernova remnants (SNRs). X-rays of synchrotron origin exhibit linear polarization in a regular, non-randomly oriented magnetic field. The significant polarized X-ray emission from four such SNRs has already been reported on the basis of observations with the Imaging X-ray Polarimetry Explorer (IXPE). The magnetic-field struct… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.20582v1-abstract-full').style.display = 'inline'; document.getElementById('2410.20582v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.20582v1-abstract-full" style="display: none;"> Synchrotron X-ray emission has been detected from nearly a dozen young supernova remnants (SNRs). X-rays of synchrotron origin exhibit linear polarization in a regular, non-randomly oriented magnetic field. The significant polarized X-ray emission from four such SNRs has already been reported on the basis of observations with the Imaging X-ray Polarimetry Explorer (IXPE). The magnetic-field structure as derived from IXPE observations is radial for Cassiopeia A, Tycho's SNR, and SN 1006, and tangential for RX J1713.7-3946. The latter together with the recent detection of a tangential magnetic field in SNR 1E 0102.2-7219 by the Australia Telescope Compact Array in the radio band shows that tangential magnetic fields can also be present in young SNRs. Thus, the dichotomy in polarization between young and middle-aged SNRs (radial magnetic fields in young SNRs, but tangential magnetic fields in middle-aged SNRs), previously noticed in the radio band, deserves additional attention. The present analysis of IXPE observations determines, for the first time, a magnetic-field structure in the northwestern rim of Vela Jr, also known as RX J0852.0-4622, and provides a new example of a young SNR with a tangential magnetic field. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.20582v1-abstract-full').style.display = 'none'; document.getElementById('2410.20582v1-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, 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">Accepted for publication in Astronomy and Astrophysics</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.19983">arXiv:2410.19983</a> <span> [<a href="https://arxiv.org/pdf/2410.19983">pdf</a>, <a href="https://arxiv.org/format/2410.19983">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"> A Two-Week $IXPE$ Monitoring Campaign on Mrk 421 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Maksym%2C+W+P">W. Peter Maksym</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Saade%2C+M+L">M. Lynne Saade</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Kiehlmann%2C+S">Sebastian Kiehlmann</a>, <a href="/search/astro-ph?searchtype=author&query=Matzeu%2C+G">Gabriele Matzeu</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Ehlert%2C+S+R">Steven R. Ehlert</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">Philip Kaaret</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Pacciani%2C+L">Luigi Pacciani</a>, <a href="/search/astro-ph?searchtype=author&query=Perri%2C+M">Matteo Perri</a>, <a href="/search/astro-ph?searchtype=author&query=Puccetti%2C+S">Simonetta Puccetti</a>, <a href="/search/astro-ph?searchtype=author&query=Kouch%2C+P+M">Pouya M. Kouch</a>, <a href="/search/astro-ph?searchtype=author&query=Lindfors%2C+E">Elina Lindfors</a>, <a href="/search/astro-ph?searchtype=author&query=Aceituno%2C+F+J">Francisco Jos茅 Aceituno</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">Giacomo Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Casanova%2C+V">V铆ctor Casanova</a>, <a href="/search/astro-ph?searchtype=author&query=Escudero%2C+J">Juan Escudero</a>, <a href="/search/astro-ph?searchtype=author&query=Ag%C3%ADs-Gonz%C3%A1lez%2C+B">Beatriz Ag铆s-Gonz谩lez</a>, <a href="/search/astro-ph?searchtype=author&query=Husillos%2C+C">C茅sar Husillos</a> , et al. (131 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="2410.19983v1-abstract-short" style="display: inline;"> X-ray polarization is a unique new probe of the particle acceleration in astrophysical jets made possible through the Imaging X-ray Polarimetry Explorer. Here we report on the first dense X-ray polarization monitoring campaign on the blazar Mrk 421. Our observations were accompanied by an even denser radio and optical polarization campaign. We find significant short-timescale variability in both X… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.19983v1-abstract-full').style.display = 'inline'; document.getElementById('2410.19983v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.19983v1-abstract-full" style="display: none;"> X-ray polarization is a unique new probe of the particle acceleration in astrophysical jets made possible through the Imaging X-ray Polarimetry Explorer. Here we report on the first dense X-ray polarization monitoring campaign on the blazar Mrk 421. Our observations were accompanied by an even denser radio and optical polarization campaign. We find significant short-timescale variability in both X-ray polarization degree and angle, including a $\sim90^\circ$ angle rotation about the jet axis. We attribute this to random variations of the magnetic field, consistent with the presence of turbulence but also unlikely to be explained by turbulence alone. At the same time, the degree of lower-energy polarization is significantly lower and shows no more than mild variability. Our campaign provides further evidence for a scenario in which energy-stratified shock-acceleration of relativistic electrons, combined with a turbulent magnetic field, is responsible for optical to X-ray synchrotron emission in blazar jets. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.19983v1-abstract-full').style.display = 'none'; document.getElementById('2410.19983v1-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 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">23 pages, including 8 pages of appendices. 12 figures, 3 tables. Submitted to 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/2407.17243">arXiv:2407.17243</a> <span> [<a href="https://arxiv.org/pdf/2407.17243">pdf</a>, <a href="https://arxiv.org/format/2407.17243">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/10.1051/0004-6361/202451645">10.1051/0004-6361/202451645 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A second view on the X-ray polarization of NGC 4151 with IXPE </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Gianolli%2C+V+E">V. E. Gianolli</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">S. Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Kammoun%2C+E">E. Kammoun</a>, <a href="/search/astro-ph?searchtype=author&query=Gnarini%2C+A">A. Gnarini</a>, <a href="/search/astro-ph?searchtype=author&query=Marinucci%2C+A">A. Marinucci</a>, <a href="/search/astro-ph?searchtype=author&query=Ursini%2C+F">F. Ursini</a>, <a href="/search/astro-ph?searchtype=author&query=Parra%2C+M">M. Parra</a>, <a href="/search/astro-ph?searchtype=author&query=Tortosa%2C+A">A. Tortosa</a>, <a href="/search/astro-ph?searchtype=author&query=De+Rosa%2C+A">A. De Rosa</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">D. E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Marin%2C+F">F. Marin</a>, <a href="/search/astro-ph?searchtype=author&query=Matt%2C+G">G. Matt</a>, <a href="/search/astro-ph?searchtype=author&query=Serafinelli%2C+R">R. Serafinelli</a>, <a href="/search/astro-ph?searchtype=author&query=Soffitta%2C+P">P. Soffitta</a>, <a href="/search/astro-ph?searchtype=author&query=Tagliacozzo%2C+D">D. Tagliacozzo</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">L. Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Done%2C+C">C. Done</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">H. L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">R. Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Mikusincova%2C+R">R. Mikusincova</a>, <a href="/search/astro-ph?searchtype=author&query=Petrucci%2C+P">P-O. Petrucci</a>, <a href="/search/astro-ph?searchtype=author&query=Ravi%2C+S">S. Ravi</a>, <a href="/search/astro-ph?searchtype=author&query=Svoboda%2C+J">J. Svoboda</a>, <a href="/search/astro-ph?searchtype=author&query=Tombesi%2C+F">F. Tombesi</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="2407.17243v2-abstract-short" style="display: inline;"> We report on the second observing program of the active galactic nucleus NGC 4151 with simultaneous Imaging X-ray Polarimetry Explorer (IXPE; {\sim}750 ks), NuSTAR ({\sim}60 ks), XMM-Newton ({\sim}75 ks), and NICER ({\sim}65 ks) pointings. NGC 4151 is the first Type 1 radio-quiet Seyfert galaxy with constrained polarization properties for the X-ray corona. Despite the lower flux state in which the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.17243v2-abstract-full').style.display = 'inline'; document.getElementById('2407.17243v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.17243v2-abstract-full" style="display: none;"> We report on the second observing program of the active galactic nucleus NGC 4151 with simultaneous Imaging X-ray Polarimetry Explorer (IXPE; {\sim}750 ks), NuSTAR ({\sim}60 ks), XMM-Newton ({\sim}75 ks), and NICER ({\sim}65 ks) pointings. NGC 4151 is the first Type 1 radio-quiet Seyfert galaxy with constrained polarization properties for the X-ray corona. Despite the lower flux state in which the source is re-observed and the resulting higher contribution of the constant reflection component in the IXPE energy band, our results are in agreement with the first detection. From polarimetric analysis, a polarization degree 螤 = 4.7 {\pm} 1.3 percent and angle 唯 = 77掳 {\pm} 8掳 east of north (68 percent confidence level) are derived in the 2.0 - 8.0 keV energy range. Combining the two observations leads to polarization properties that are more constrained than those of the individual detections, showing 螤 = 4.5 {\pm} 0.9 percent and 唯 = 81掳 {\pm} 6掳 (with detection significance {\sim}4.6蟽). The observed polarization angle aligns very well with the radio emission in this source, supporting, together with the significant polarization degree, a slab or wedge geometry for the X-ray corona. However, a switch in the polarization angle at low energies (37掳 {\pm} 7掳 in the 2 - 3.5 keV bin) suggests the presence of another component. When it is included in the spectro-polarimetric fit, a high polarization degree disfavors an interpretation in terms of a leakage through the absorbers, rather pointing to scattering from some kind of mirror. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.17243v2-abstract-full').style.display = 'none'; document.getElementById('2407.17243v2-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 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 8 figures, 3 tables. Accepted to 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 691, A29 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.11128">arXiv:2407.11128</a> <span> [<a href="https://arxiv.org/pdf/2407.11128">pdf</a>, <a href="https://arxiv.org/format/2407.11128">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> </div> <p class="title is-5 mathjax"> X-ray and multiwavelength polarization of Mrk 501 from 2022 to 2023 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Chen%2C+C+J">Chien-Ting J. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Ehlert%2C+S+R">Steven R. Ehlert</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Wu%2C+K">Kinwah Wu</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Mizuno%2C+T">Tsunefumi Mizuno</a>, <a href="/search/astro-ph?searchtype=author&query=Kouch%2C+P+M">Pouya M. Kouch</a>, <a href="/search/astro-ph?searchtype=author&query=Lindfors%2C+E">Elina Lindfors</a>, <a href="/search/astro-ph?searchtype=author&query=Borman%2C+G+A">George A. Borman</a>, <a href="/search/astro-ph?searchtype=author&query=Grishina%2C+T+S">Tatiana S. Grishina</a>, <a href="/search/astro-ph?searchtype=author&query=Kopatskaya%2C+E+N">Evgenia N. Kopatskaya</a>, <a href="/search/astro-ph?searchtype=author&query=Larionova%2C+E+G">Elena G. Larionova</a>, <a href="/search/astro-ph?searchtype=author&query=Morozova%2C+D+A">Daria A. Morozova</a>, <a href="/search/astro-ph?searchtype=author&query=Savchenko%2C+S+S">Sergey S. Savchenko</a>, <a href="/search/astro-ph?searchtype=author&query=Troitsky%2C+I+S">Ivan S. Troitsky</a>, <a href="/search/astro-ph?searchtype=author&query=Troitskaya%2C+Y+V">Yulia V. Troitskaya</a> , et al. (121 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.11128v1-abstract-short" style="display: inline;"> We present multiwavelength polarization measurements of the luminous blazar Mrk~501 over a 14-month period. The 2--8 keV X-ray polarization was measured with the Imaging X-ray Polarimetry Explorer (IXPE) with six 100-ks observations spanning from 2022 March to 2023 April. Each IXPE observation was accompanied by simultaneous X-ray data from NuSTAR, Swift/XRT, and/or XMM-Newton. Complementary optic… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.11128v1-abstract-full').style.display = 'inline'; document.getElementById('2407.11128v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.11128v1-abstract-full" style="display: none;"> We present multiwavelength polarization measurements of the luminous blazar Mrk~501 over a 14-month period. The 2--8 keV X-ray polarization was measured with the Imaging X-ray Polarimetry Explorer (IXPE) with six 100-ks observations spanning from 2022 March to 2023 April. Each IXPE observation was accompanied by simultaneous X-ray data from NuSTAR, Swift/XRT, and/or XMM-Newton. Complementary optical-infrared polarization measurements were also available in the B, V, R, I, and J bands, as were radio polarization measurements from 4.85 GHz to 225.5 GHz. Among the first five IXPE observations, we did not find significant variability in the X-ray polarization degree and angle with IXPE. However, the most recent sixth observation found an elevated polarization degree at $>3蟽$ above the average of the other five observations. The optical and radio measurements show no apparent correlations with the X-ray polarization properties. Throughout the six IXPE observations, the X-ray polarization degree remained higher than, or similar to, the R-band optical polarization degree, which remained higher than the radio value. This is consistent with the energy-stratified shock scenario proposed to explain the first two IXPE observations, in which the polarized X-ray, optical, and radio emission arises from different regions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.11128v1-abstract-full').style.display = 'none'; document.getElementById('2407.11128v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.04749">arXiv:2407.04749</a> <span> [<a href="https://arxiv.org/pdf/2407.04749">pdf</a>, <a href="https://arxiv.org/format/2407.04749">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="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> </div> <p class="title is-5 mathjax"> Towards imaging-spectro-polarimetry of solar flares in the X-rays </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Fabiani%2C+S">Sergio Fabiani</a>, <a href="/search/astro-ph?searchtype=author&query=Rankin%2C+J">John Rankin</a>, <a href="/search/astro-ph?searchtype=author&query=Basso%2C+S">Stefano Basso</a>, <a href="/search/astro-ph?searchtype=author&query=Costa%2C+E">Enrico Costa</a>, <a href="/search/astro-ph?searchtype=author&query=Del+Monte%2C+E">Ettore Del Monte</a>, <a href="/search/astro-ph?searchtype=author&query=Desch%2C+K">Klaus Desch</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Gruber%2C+M">Markus Gruber</a>, <a href="/search/astro-ph?searchtype=author&query=Kaminski%2C+J">Jochen Kaminski</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Imtiaz%2C+S">Saba Imtiaz</a>, <a href="/search/astro-ph?searchtype=author&query=Lefevre%2C+C">Carlo Lefevre</a>, <a href="/search/astro-ph?searchtype=author&query=Loffredo%2C+P">Pasqualino Loffredo</a>, <a href="/search/astro-ph?searchtype=author&query=Manikantan%2C+H">Hemant Manikantan</a>, <a href="/search/astro-ph?searchtype=author&query=Morbidini%2C+A">Alfredo Morbidini</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Pareschi%2C+G">Giovanni Pareschi</a>, <a href="/search/astro-ph?searchtype=author&query=Plesanovs%2C+V">Vladilavs Plesanovs</a>, <a href="/search/astro-ph?searchtype=author&query=Ratheesh%2C+A">Ajay Ratheesh</a>, <a href="/search/astro-ph?searchtype=author&query=Rubini%2C+A">Alda Rubini</a>, <a href="/search/astro-ph?searchtype=author&query=Soffitta%2C+P">Paolo Soffitta</a>, <a href="/search/astro-ph?searchtype=author&query=Spiga%2C+D">Daniele Spiga</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="2407.04749v1-abstract-short" style="display: inline;"> X-ray polarimetry of solar flares is still a not well established field of observation of our star. Past polarimeters were not able to measure with a high significance the polarization in X-rays from solar flares. Moreover, they had no imaging capabilities and measured only the polarization by integrating on all the image of the source. We propose a mission concept based on a gas photoelectric pol… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.04749v1-abstract-full').style.display = 'inline'; document.getElementById('2407.04749v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.04749v1-abstract-full" style="display: none;"> X-ray polarimetry of solar flares is still a not well established field of observation of our star. Past polarimeters were not able to measure with a high significance the polarization in X-rays from solar flares. Moreover, they had no imaging capabilities and measured only the polarization by integrating on all the image of the source. We propose a mission concept based on a gas photoelectric polarimeter, coupled with multilayer lobster-eye optics, to perform imaging-spectro-polarimetry of solar flares while monitoring the entire solar disc. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.04749v1-abstract-full').style.display = 'none'; document.getElementById('2407.04749v1-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 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Proceeding of SPIE Conference "Astronomical Telescopes+ Instrumentation", Yokohama (Japan), 16-21 June 2024</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> Paper No. 13093-311 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.19519">arXiv:2406.19519</a> <span> [<a href="https://arxiv.org/pdf/2406.19519">pdf</a>, <a href="https://arxiv.org/format/2406.19519">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/10.36116/MEMSAIT_95N1.2024.27">10.36116/MEMSAIT_95N1.2024.27 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Unobscured radio-quiet Active Galactic Nuclei under the eyes of IXPE </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Gianolli%2C+V+E">V. E. Gianolli</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">S. Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Petrucci%2C+P">P-O. Petrucci</a>, <a href="/search/astro-ph?searchtype=author&query=Marinucci%2C+A">A. Marinucci</a>, <a href="/search/astro-ph?searchtype=author&query=Ingram%2C+A">A. Ingram</a>, <a href="/search/astro-ph?searchtype=author&query=Tagliacozzo%2C+D">D. Tagliacozzo</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">D. E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Marin%2C+F">F. Marin</a>, <a href="/search/astro-ph?searchtype=author&query=Matt%2C+G">G. Matt</a>, <a href="/search/astro-ph?searchtype=author&query=Soffitta%2C+P">P. Soffitta</a>, <a href="/search/astro-ph?searchtype=author&query=Tombesi%2C+F">F. Tombesi</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="2406.19519v1-abstract-short" style="display: inline;"> We present the results of the X-ray polarimetric analyses performed on unobscured radio-quiet Active Galactic Nuclei (AGN) with the Imaging X-ray Polarimetry Explorer (IXPE), with simultaneous XMM-Newton and NuSTAR data. The synergy of these instruments is crucial to constrain the X-ray corona physical properties and assess its geometry. In the first two years of operation, three AGN have been obs… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.19519v1-abstract-full').style.display = 'inline'; document.getElementById('2406.19519v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.19519v1-abstract-full" style="display: none;"> We present the results of the X-ray polarimetric analyses performed on unobscured radio-quiet Active Galactic Nuclei (AGN) with the Imaging X-ray Polarimetry Explorer (IXPE), with simultaneous XMM-Newton and NuSTAR data. The synergy of these instruments is crucial to constrain the X-ray corona physical properties and assess its geometry. In the first two years of operation, three AGN have been observed: significant polarization was detected for NGC 4151 (4.9$\pm$1.1 per cent) and IC 4329A (albeit with less confidence, 3.3$\pm$1.1 per cent), with polarization angles aligned with their radio jets, while only an upper limit was found for MCG-05-23-16 ($<$3.2 per cent). Monte Carlo simulations, conducted to investigate the coronal geometry of these AGN, favor a radially extended corona geometry in NGC 4151 and IC 4329A, a scenario consistent also with MCG-05-23-16, if the disk inclination angle is below 50$^\circ$. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.19519v1-abstract-full').style.display = 'none'; document.getElementById('2406.19519v1-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 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Proceeding of the 12th Young Researcher Meeting. Published in Memorie della Societ脿 Astronomica Italiana (MemSAIt)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Vol 95, 2024, page 27 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.01693">arXiv:2406.01693</a> <span> [<a href="https://arxiv.org/pdf/2406.01693">pdf</a>, <a href="https://arxiv.org/format/2406.01693">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/10.1051/0004-6361/202449166">10.1051/0004-6361/202449166 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> IXPE observation of PKS 2155-304 reveals the most highly polarized blazar </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kouch%2C+P+M">Pouya M. Kouch</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Tavecchio%2C+F">Fabrizio Tavecchio</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Ehlert%2C+S+R">Steven R. Ehlert</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Madejski%2C+G+M">Grzegorz M. Madejski</a>, <a href="/search/astro-ph?searchtype=author&query=Romani%2C+R+W">Roger W. Romani</a>, <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Lindfors%2C+E">Elina Lindfors</a>, <a href="/search/astro-ph?searchtype=author&query=Nilsson%2C+K">Kari Nilsson</a>, <a href="/search/astro-ph?searchtype=author&query=Toppari%2C+E">Ella Toppari</a>, <a href="/search/astro-ph?searchtype=author&query=Potter%2C+S+B">Stephen B. Potter</a>, <a href="/search/astro-ph?searchtype=author&query=Imazawa%2C+R">Ryo Imazawa</a>, <a href="/search/astro-ph?searchtype=author&query=Sasada%2C+M">Mahito Sasada</a>, <a href="/search/astro-ph?searchtype=author&query=Fukazawa%2C+Y">Yasushi Fukazawa</a>, <a href="/search/astro-ph?searchtype=author&query=Kawabata%2C+K+S">Koji S. Kawabata</a>, <a href="/search/astro-ph?searchtype=author&query=Uemura%2C+M">Makoto Uemura</a>, <a href="/search/astro-ph?searchtype=author&query=Mizuno%2C+T">Tsunefumi Mizuno</a>, <a href="/search/astro-ph?searchtype=author&query=Nakaoka%2C+T">Tatsuya Nakaoka</a> , et al. (111 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2406.01693v1-abstract-short" style="display: inline;"> We report the X-ray polarization properties of the high-synchrotron-peaked (HSP) blazar PKS 2155$-$304 based on observations with the Imaging X-ray Polarimetry Explorer (IXPE). We observed the source between Oct 27 and Nov 7, 2023. We also conducted an extensive contemporaneous multiwavelength (MW) campaign. We find that during the first half ($T_1$) of the IXPE pointing, the source exhibited the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.01693v1-abstract-full').style.display = 'inline'; document.getElementById('2406.01693v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.01693v1-abstract-full" style="display: none;"> We report the X-ray polarization properties of the high-synchrotron-peaked (HSP) blazar PKS 2155$-$304 based on observations with the Imaging X-ray Polarimetry Explorer (IXPE). We observed the source between Oct 27 and Nov 7, 2023. We also conducted an extensive contemporaneous multiwavelength (MW) campaign. We find that during the first half ($T_1$) of the IXPE pointing, the source exhibited the highest X-ray polarization degree detected for an HSP blazar thus far, (30.7$\pm$2.0)%, which dropped to (15.3$\pm$2.1)% during the second half ($T_2$). The X-ray polarization angle remained stable during the IXPE pointing at 129.4$^\circ$$\pm$1.8$^\circ$ and 125.4$^\circ$$\pm$3.9$^\circ$ during $T_1$ and $T_2$, respectively. Meanwhile, the optical polarization degree remained stable during the IXPE pointing, with average host-galaxy-corrected values of (4.3$\pm$0.7)% and (3.8$\pm$0.9)% during the $T_1$ and $T_2$, respectively. During the IXPE pointing, the optical polarization angle changed achromatically from $\sim$140$^\circ$ to $\sim$90$^\circ$ and back to $\sim$130$^\circ$. Despite several attempts, we only detected (99.7% conf.) the radio polarization once (during $T_2$, at 225.5 GHz): with degree (1.7$\pm$0.4)% and angle 112.5$^\circ$$\pm$5.5$^\circ$. The direction of the broad pc-scale jet is rather ambiguous and has been found to point to the east and south at different epochs; however, on larger scales (> 1.5 pc) the jet points toward the southeast ($\sim$135$^\circ$), similar to all of the MW polarization angles. Moreover, the X-ray to optical polarization degree ratios of $\sim$7 and $\sim$4 during $T_1$ and $T_2$, respectively, are similar to previous IXPE results for several HSP blazars. These findings, combined with the lack of correlation of temporal variability between the MW polarization properties, agree with an energy-stratified shock-acceleration scenario in HSP blazars. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.01693v1-abstract-full').style.display = 'none'; document.getElementById('2406.01693v1-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 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">17 pages, 10 figures, 4 tables, Accepted for publication in A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 689, A119 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2405.07577">arXiv:2405.07577</a> <span> [<a href="https://arxiv.org/pdf/2405.07577">pdf</a>, <a href="https://arxiv.org/format/2405.07577">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/2041-8213/ad4a68">10.3847/2041-8213/ad4a68 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Discovery of a shock-compressed magnetic field in the north-western rim of the young supernova remnant RX J1713.7-3946 with X-ray polarimetry </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ferrazzoli%2C+R">Riccardo Ferrazzoli</a>, <a href="/search/astro-ph?searchtype=author&query=Prokhorov%2C+D">Dmitry Prokhorov</a>, <a href="/search/astro-ph?searchtype=author&query=Bucciantini%2C+N">Niccol貌 Bucciantini</a>, <a href="/search/astro-ph?searchtype=author&query=Slane%2C+P">Patrick Slane</a>, <a href="/search/astro-ph?searchtype=author&query=Vink%2C+J">Jacco Vink</a>, <a href="/search/astro-ph?searchtype=author&query=Cardillo%2C+M">Martina Cardillo</a>, <a href="/search/astro-ph?searchtype=author&query=Yang%2C+Y">Yi-Jung Yang</a>, <a href="/search/astro-ph?searchtype=author&query=Silvestri%2C+S">Stefano Silvestri</a>, <a href="/search/astro-ph?searchtype=author&query=Zhou%2C+P">Ping Zhou</a>, <a href="/search/astro-ph?searchtype=author&query=Costa%2C+E">Enrico Costa</a>, <a href="/search/astro-ph?searchtype=author&query=Omodei%2C+N">Nicola Omodei</a>, <a href="/search/astro-ph?searchtype=author&query=Ng%2C+C+-">C. -Y. Ng</a>, <a href="/search/astro-ph?searchtype=author&query=Soffitta%2C+P">Paolo Soffitta</a>, <a href="/search/astro-ph?searchtype=author&query=Weisskopf%2C+M+C">Martin C. Weisskopf</a>, <a href="/search/astro-ph?searchtype=author&query=Baldini%2C+L">Luca Baldini</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">Victor Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Heyl%2C+J">Jeremy Heyl</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">Philip Kaaret</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Marin%2C+F">Fr茅d茅ric Marin</a>, <a href="/search/astro-ph?searchtype=author&query=Mizuno%2C+T">Tsunefumi Mizuno</a>, <a href="/search/astro-ph?searchtype=author&query=Pesce-Rollins%2C+M">Melissa Pesce-Rollins</a>, <a href="/search/astro-ph?searchtype=author&query=Sgr%C3%B2%2C+C">Carmelo Sgr貌</a>, <a href="/search/astro-ph?searchtype=author&query=Swartz%2C+D+A">Douglas A. Swartz</a> , et al. (77 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="2405.07577v2-abstract-short" style="display: inline;"> Supernova remnants (SNRs) provide insights into cosmic-ray acceleration and magnetic field dynamics at shock fronts. Recent X-ray polarimetric measurements by the Imaging X-ray Polarimetry Explorer (IXPE) have revealed radial magnetic fields near particle acceleration sites in young SNRs, including Cassiopeia A, Tycho, and SN 1006. We present here the spatially-resolved IXPE X-ray polarimetric obs… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.07577v2-abstract-full').style.display = 'inline'; document.getElementById('2405.07577v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.07577v2-abstract-full" style="display: none;"> Supernova remnants (SNRs) provide insights into cosmic-ray acceleration and magnetic field dynamics at shock fronts. Recent X-ray polarimetric measurements by the Imaging X-ray Polarimetry Explorer (IXPE) have revealed radial magnetic fields near particle acceleration sites in young SNRs, including Cassiopeia A, Tycho, and SN 1006. We present here the spatially-resolved IXPE X-ray polarimetric observation of the northwestern rim of SNR RX J1713.7-3946. For the first time, our analysis shows that the magnetic field in particle acceleration sites of this SNR is oriented tangentially with respect to the shock front. Because of the lack of precise Faraday-rotation measurements in the radio band, this was not possible before. The average measured polarization degree (PD) of the synchtrotron emission is 12.5 {\pm} 3.3%, lower than the one measured by IXPE in SN 1006, comparable to the Tycho one, but notably higher than the one in Cassiopeia A. On sub-parsec scales, localized patches within RX J1713.7-3946 display PD up to 41.5 {\pm} 9.5%. These results are compatible with a shock-compressed magnetic field. However, in order to explain the observed PD, either the presence of a radial net magnetic field upstream of the shock, or partial reisotropization of the turbulence downstream by radial magneto-hydrodynamical instabilities, can be invoked. From comparison of PD and magnetic field distribution with 纬-rays and 12 CO data, our results provide new inputs in favor of a leptonic origin of the 纬-ray emission. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.07577v2-abstract-full').style.display = 'none'; document.getElementById('2405.07577v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">18 pages, 6 figures, 2 tables, published in ApJ Letters</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJL 967 L38 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.14200">arXiv:2404.14200</a> <span> [<a href="https://arxiv.org/pdf/2404.14200">pdf</a>, <a href="https://arxiv.org/format/2404.14200">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"> Investigating the Properties of the Relativistic Jet and Hot Corona in AGN with X-ray Polarimetry </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Marin%2C+F">Fr茅d茅ric Marin</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=Matt%2C+G">Giorgio Matt</a>, <a href="/search/astro-ph?searchtype=author&query=Soffitta%2C+P">Paolo Soffitta</a>, <a href="/search/astro-ph?searchtype=author&query=Tombesi%2C+F">Francesco Tombesi</a>, <a href="/search/astro-ph?searchtype=author&query=Costa%2C+E">Enrico Costa</a>, <a href="/search/astro-ph?searchtype=author&query=Donnarumma%2C+I">Immacolata Donnarumma</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="2404.14200v1-abstract-short" style="display: inline;"> X-ray polarimetry has been suggested as a prominent tool for investigating the geometrical and physical properties of the emissions from active galactic nuclei (AGN). The successful launch of the Imaging X-ray Polarimetry Explorer (IXPE) on 9 December 2021 has expanded the previously restricted scope of polarimetry into the X-ray domain, enabling X-ray polarimetric studies of AGN. Over a span of t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.14200v1-abstract-full').style.display = 'inline'; document.getElementById('2404.14200v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.14200v1-abstract-full" style="display: none;"> X-ray polarimetry has been suggested as a prominent tool for investigating the geometrical and physical properties of the emissions from active galactic nuclei (AGN). The successful launch of the Imaging X-ray Polarimetry Explorer (IXPE) on 9 December 2021 has expanded the previously restricted scope of polarimetry into the X-ray domain, enabling X-ray polarimetric studies of AGN. Over a span of two years, IXPE has observed various AGN populations, including blazars and radio-quiet AGN. In this paper, we summarize the remarkable discoveries achieved thanks to the opening of the new window of X-ray polarimetry of AGN through IXPE observations. We will delve into two primary areas of interest: first, the magnetic field geometry and particle acceleration mechanisms in the jets of radio-loud AGN, such as blazars, where the relativistic acceleration process dominates the spectral energy distribution; and second, the geometry of the hot corona in radio-quiet AGN. Thus far, the IXPE results from blazars favor the energy-stratified shock acceleration model, and they provide evidence of helical magnetic fields inside the jet. Concerning the corona geometry, the IXPE results are consistent with a disk-originated slab-like or wedge-like shape, as could result from Comptonization around the accretion disk. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.14200v1-abstract-full').style.display = 'none'; document.getElementById('2404.14200v1-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 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">16 pages, 5 figures, 2 tables; Accepted for publication in Galaxies, Special Issue "Multi-Phase Fueling and Feedback Processes in Jetted 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/2403.02061">arXiv:2403.02061</a> <span> [<a href="https://arxiv.org/pdf/2403.02061">pdf</a>, <a href="https://arxiv.org/format/2403.02061">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/10.1051/0004-6361/202449760">10.1051/0004-6361/202449760 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> X-ray polarization measurement of the gold standard of radio-quiet active galactic nuclei : NGC 1068 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Marin%2C+F">F. Marin</a>, <a href="/search/astro-ph?searchtype=author&query=Marinucci%2C+A">A. Marinucci</a>, <a href="/search/astro-ph?searchtype=author&query=Laurenti%2C+M">M. Laurenti</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">D. E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Barnouin%2C+T">T. Barnouin</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">A. Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Ursini%2C+F">F. Ursini</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">S. Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Ravi%2C+S">S. Ravi</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">H. L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Matt%2C+G">G. Matt</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+C+-">C. -T. Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Gianolli%2C+V+E">V. E. Gianolli</a>, <a href="/search/astro-ph?searchtype=author&query=Ingram%2C+A">A. Ingram</a>, <a href="/search/astro-ph?searchtype=author&query=Maksym%2C+W+P">W. P. Maksym</a>, <a href="/search/astro-ph?searchtype=author&query=Panagiotou%2C+C">C. Panagiotou</a>, <a href="/search/astro-ph?searchtype=author&query=Podgorny%2C+J">J. Podgorny</a>, <a href="/search/astro-ph?searchtype=author&query=Puccetti%2C+S">S. Puccetti</a>, <a href="/search/astro-ph?searchtype=author&query=Ratheesh%2C+A">A. Ratheesh</a>, <a href="/search/astro-ph?searchtype=author&query=Tombesi%2C+F">F. Tombesi</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">I. Agudo</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=Bachetti%2C+M">M. Bachetti</a>, <a href="/search/astro-ph?searchtype=author&query=Baldini%2C+L">L. Baldini</a>, <a href="/search/astro-ph?searchtype=author&query=Baumgartner%2C+W">W. Baumgartner</a> , et al. (80 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="2403.02061v2-abstract-short" style="display: inline;"> We used the Imaging X-ray Polarimetry Explorer (IXPE) satellite to measure, for the first time, the 2-8 keV polarization of NGC 1068. We pointed IXPE for a net exposure time of 1.15 Ms on the target, in addition to two ~ 10 ks each Chandra snapshots in order to account for the potential impact of several ultraluminous X-ray source (ULXs) within IXPE's field-of-view. We measured a 2 - 8 keV polariz… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.02061v2-abstract-full').style.display = 'inline'; document.getElementById('2403.02061v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.02061v2-abstract-full" style="display: none;"> We used the Imaging X-ray Polarimetry Explorer (IXPE) satellite to measure, for the first time, the 2-8 keV polarization of NGC 1068. We pointed IXPE for a net exposure time of 1.15 Ms on the target, in addition to two ~ 10 ks each Chandra snapshots in order to account for the potential impact of several ultraluminous X-ray source (ULXs) within IXPE's field-of-view. We measured a 2 - 8 keV polarization degree of 12.4% +/- 3.6% and an electric vector polarization angle of 101掳 +/- 8掳 at 68% confidence level. If we exclude the spectral region containing the bright Fe K lines and other soft X-ray lines where depolarization occurs, the polarization fraction rises up to 21.3% +/- 6.7% in the 3.5 - 6.0 keV band, with a similar polarization angle. The observed polarization angle is found to be perpendicular to the parsec scale radio jet. Using a combined Chandra and IXPE analysis plus multi-wavelength constraints, we estimated that the circumnuclear "torus" may sustain a half-opening angle of 50掳 - 55掳 (from the vertical axis of the system). Thanks to IXPE, we have measured the X-ray polarization of NGC 1068 and found comparable results, both in terms of polarization angle orientation with respect to the radio-jet and torus half-opening angle, to the X-ray polarimetric measurement achieved for the other archetypal Compton-thick AGN : the Circinus galaxy. Probing the geometric arrangement of parsec-scale matter in extragalactic object is now feasible thanks to X-ray polarimetry. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.02061v2-abstract-full').style.display = 'none'; document.getElementById('2403.02061v2-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 May, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 4 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 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">9 pages, 5 figures, 2 tables, submited to A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">MSC Class:</span> 85-06 <span class="has-text-black-bis has-text-weight-semibold">ACM Class:</span> J.2.3; J.2.9 </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 689, A238 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.04420">arXiv:2401.04420</a> <span> [<a href="https://arxiv.org/pdf/2401.04420">pdf</a>, <a href="https://arxiv.org/format/2401.04420">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/ad1ce4">10.3847/1538-4357/ad1ce4 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Detection of X-ray Polarization from the Blazar 1ES 1959+650 with the Imaging X-ray Polarimetry Explorer </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Errando%2C+M">Manel Errando</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Peirson%2C+A+L">Abel Lawrence Peirson</a>, <a href="/search/astro-ph?searchtype=author&query=Perri%2C+M">Matteo Perri</a>, <a href="/search/astro-ph?searchtype=author&query=Puccetti%2C+S">Simonetta Puccetti</a>, <a href="/search/astro-ph?searchtype=author&query=Rabinowitz%2C+P+L">Pazit L. Rabinowitz</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Savchenko%2C+S+S">Sergey S. Savchenko</a>, <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D">Dmitry Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Bourbah%2C+I+G">Ioakeim G. Bourbah</a>, <a href="/search/astro-ph?searchtype=author&query=Kiehlmann%2C+S">Sebastian Kiehlmann</a>, <a href="/search/astro-ph?searchtype=author&query=Kontopodis%2C+E">Evangelos Kontopodis</a>, <a href="/search/astro-ph?searchtype=author&query=Mandarakas%2C+N">Nikos Mandarakas</a>, <a href="/search/astro-ph?searchtype=author&query=Romanopoulos%2C+S">Stylianos Romanopoulos</a>, <a href="/search/astro-ph?searchtype=author&query=Skalidis%2C+R">Raphael Skalidis</a>, <a href="/search/astro-ph?searchtype=author&query=Vervelaki%2C+A">Anna Vervelaki</a>, <a href="/search/astro-ph?searchtype=author&query=Aceituno%2C+F+J">Francisco Jos茅 Aceituno</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardos%2C+M+I">Maria I. Bernardos</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">Giacomo Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Casanova%2C+V">V铆ctor Casanova</a> , et al. (121 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2401.04420v1-abstract-short" style="display: inline;"> Observations of linear polarization in the 2-8 keV energy range with the Imaging X-ray Polarimetry Explorer (IXPE) explore the magnetic field geometry and dynamics of the regions generating non-thermal radiation in relativistic jets of blazars. These jets, particularly in blazars whose spectral energy distribution peaks at X-ray energies, emit X-rays via synchrotron radiation from high-energy part… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.04420v1-abstract-full').style.display = 'inline'; document.getElementById('2401.04420v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.04420v1-abstract-full" style="display: none;"> Observations of linear polarization in the 2-8 keV energy range with the Imaging X-ray Polarimetry Explorer (IXPE) explore the magnetic field geometry and dynamics of the regions generating non-thermal radiation in relativistic jets of blazars. These jets, particularly in blazars whose spectral energy distribution peaks at X-ray energies, emit X-rays via synchrotron radiation from high-energy particles within the jet. IXPE observations of the X-ray selected BL Lac-type blazar 1ES 1959+650 in 2022 May 3-4 showed a significant linear polarization degree of $螤_\mathrm{x} = 8.0\% \pm 2.3\%$ at an electric-vector position angle $蠄_\mathrm{x} = 123^\circ \pm 8^\circ$. However, in 2022 June 9-12, only an upper limit of $螤_\mathrm{x} \leq 5.1\%$ could be derived (at the 99% confidence level). The degree of optical polarization at that time $螤_\mathrm{O} \sim 5\%$ is comparable to the X-ray measurement. We investigate possible scenarios for these findings, including temporal and geometrical depolarization effects. Unlike some other X-ray selected BL Lac objects, there is no significant chromatic dependence of the measured polarization in 1ES 1959+650, and its low X-ray polarization may be attributed to turbulence in the jet flow with dynamical timescales shorter than 1 day. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.04420v1-abstract-full').style.display = 'none'; document.getElementById('2401.04420v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">16 pages, 4 figures, accepted for publication in The Astrophysical Journal</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> The Astrophysical Journal, 963 (2024) 5 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.10732">arXiv:2312.10732</a> <span> [<a href="https://arxiv.org/pdf/2312.10732">pdf</a>, <a href="https://arxiv.org/format/2312.10732">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> First characterization of the emission behavior of Mrk421 from radio to VHE gamma rays with simultaneous X-ray polarization measurements </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Abe%2C+S">S. Abe</a>, <a href="/search/astro-ph?searchtype=author&query=Abhir%2C+J">J. Abhir</a>, <a href="/search/astro-ph?searchtype=author&query=Acciari%2C+V+A">V. A. Acciari</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">I. Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Aniello%2C+T">T. Aniello</a>, <a href="/search/astro-ph?searchtype=author&query=Ansoldi%2C+S">S. Ansoldi</a>, <a href="/search/astro-ph?searchtype=author&query=Antonelli%2C+L+A">L. A. Antonelli</a>, <a href="/search/astro-ph?searchtype=author&query=Engels%2C+A+A">A. Arbet Engels</a>, <a href="/search/astro-ph?searchtype=author&query=Arcaro%2C+C">C. Arcaro</a>, <a href="/search/astro-ph?searchtype=author&query=Artero%2C+M">M. Artero</a>, <a href="/search/astro-ph?searchtype=author&query=Asano%2C+K">K. Asano</a>, <a href="/search/astro-ph?searchtype=author&query=Babi%C4%87%2C+A">A. Babi膰</a>, <a href="/search/astro-ph?searchtype=author&query=Baquero%2C+A">A. Baquero</a>, <a href="/search/astro-ph?searchtype=author&query=de+Almeida%2C+U+B">U. Barres de Almeida</a>, <a href="/search/astro-ph?searchtype=author&query=Barrio%2C+J+A">J. A. Barrio</a>, <a href="/search/astro-ph?searchtype=author&query=Batkovi%C4%87%2C+I">I. Batkovi膰</a>, <a href="/search/astro-ph?searchtype=author&query=Baxter%2C+J">J. Baxter</a>, <a href="/search/astro-ph?searchtype=author&query=Gonz%C3%A1lez%2C+J+B">J. Becerra Gonz谩lez</a>, <a href="/search/astro-ph?searchtype=author&query=Bednarek%2C+W">W. Bednarek</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardini%2C+E">E. Bernardini</a>, <a href="/search/astro-ph?searchtype=author&query=Bernete%2C+J">J. Bernete</a>, <a href="/search/astro-ph?searchtype=author&query=Berti%2C+A">A. Berti</a>, <a href="/search/astro-ph?searchtype=author&query=Besenrieder%2C+J">J. Besenrieder</a>, <a href="/search/astro-ph?searchtype=author&query=Bigongiari%2C+C">C. Bigongiari</a>, <a href="/search/astro-ph?searchtype=author&query=Biland%2C+A">A. Biland</a> , et al. (229 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2312.10732v1-abstract-short" style="display: inline;"> We perform the first broadband study of Mrk421 from radio to TeV gamma rays with simultaneous measurements of the X-ray polarization from IXPE. The data were collected within an extensive multiwavelength campaign organized between May and June 2022 using MAGIC, Fermi-LAT, NuSTAR, XMM-Newton, Swift, and several optical and radio telescopes to complement IXPE. During the IXPE exposures, the measured… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.10732v1-abstract-full').style.display = 'inline'; document.getElementById('2312.10732v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.10732v1-abstract-full" style="display: none;"> We perform the first broadband study of Mrk421 from radio to TeV gamma rays with simultaneous measurements of the X-ray polarization from IXPE. The data were collected within an extensive multiwavelength campaign organized between May and June 2022 using MAGIC, Fermi-LAT, NuSTAR, XMM-Newton, Swift, and several optical and radio telescopes to complement IXPE. During the IXPE exposures, the measured 0.2-1 TeV flux is close to the quiescent state and ranges from 25% to 50% of the Crab Nebula without intra-night variability. Throughout the campaign, the VHE and X-ray emission are positively correlated at a $4蟽$ significance level. The IXPE measurements unveil a X-ray polarization degree that is a factor of 2-5 higher than in the optical/radio bands; that implies an energy-stratified jet in which the VHE photons are emitted co-spatially with the X-rays, in the vicinity of a shock front. The June 2022 observations exhibit a rotation of the X-ray polarization angle. Despite no simultaneous VHE coverage being available during a large fraction of the swing, the Swift-XRT monitoring unveils an X-ray flux increase with a clear spectral hardening. It suggests that flares in high synchrotron peaked blazars can be accompanied by a polarization angle rotation, as observed in some flat spectrum radio quasars. Finally, during the polarization angle rotation, NuSTAR data reveal two contiguous spectral hysteresis loops in opposite directions (clockwise and counter-clockwise), implying important changes in the particle acceleration efficiency on $\sim$hour timescales. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.10732v1-abstract-full').style.display = 'none'; document.getElementById('2312.10732v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in Astronomy & Astrophysics. 29 pages, 22 figures. Corresponding authors: Axel Arbet Engels, Felix Schmuckermaier, David Paneque</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.04421">arXiv:2312.04421</a> <span> [<a href="https://arxiv.org/pdf/2312.04421">pdf</a>, <a href="https://arxiv.org/format/2312.04421">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/10.1051/0004-6361/202349080">10.1051/0004-6361/202349080 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Pulsar-wind-nebula-powered Galactic center X-ray filament G0.13-0.11: Proof of the synchrotron nature by IXPE </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Churazov%2C+E">Eugene Churazov</a>, <a href="/search/astro-ph?searchtype=author&query=Khabibullin%2C+I">Ildar Khabibullin</a>, <a href="/search/astro-ph?searchtype=author&query=Barnouin%2C+T">Thibault Barnouin</a>, <a href="/search/astro-ph?searchtype=author&query=Bucciantini%2C+N">Niccol貌 Bucciantini</a>, <a href="/search/astro-ph?searchtype=author&query=Costa%2C+E">Enrico Costa</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Ferrazzoli%2C+R">Riccardo Ferrazzoli</a>, <a href="/search/astro-ph?searchtype=author&query=Forman%2C+W">William Forman</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">Philip Kaaret</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Kolodziejczak%2C+J+J">Jeffery J. Kolodziejczak</a>, <a href="/search/astro-ph?searchtype=author&query=Kraft%2C+R">Ralph Kraft</a>, <a href="/search/astro-ph?searchtype=author&query=Marin%2C+F">Fr茅d茅ric Marin</a>, <a href="/search/astro-ph?searchtype=author&query=Matt%2C+G">Giorgio Matt</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Romani%2C+R+W">Roger W. Romani</a>, <a href="/search/astro-ph?searchtype=author&query=Silvestri%2C+S">Stefano Silvestri</a>, <a href="/search/astro-ph?searchtype=author&query=Soffitta%2C+P">Paolo Soffitta</a>, <a href="/search/astro-ph?searchtype=author&query=Sunyaev%2C+R">Rashid Sunyaev</a>, <a href="/search/astro-ph?searchtype=author&query=Svoboda%2C+J">Jiri Svoboda</a>, <a href="/search/astro-ph?searchtype=author&query=Vikhlinin%2C+A">Alexey Vikhlinin</a>, <a href="/search/astro-ph?searchtype=author&query=Weisskopf%2C+M+C">Martin C. Weisskopf</a>, <a href="/search/astro-ph?searchtype=author&query=Xie%2C+F">Fei Xie</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a> , et al. (81 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="2312.04421v2-abstract-short" style="display: inline;"> We report the discovery of X-ray polarization from the X-ray-bright filament. G0.13-0.11 in the Galactic center (GC) region. This filament features a bright, hard X-ray source that is most plausibly a pulsar wind nebula (PWN) and an extended and structured diffuse component. Combining the polarization signal from IXPE with the imaging/spectroscopic data from Chandra, we find that X-ray emission of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.04421v2-abstract-full').style.display = 'inline'; document.getElementById('2312.04421v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.04421v2-abstract-full" style="display: none;"> We report the discovery of X-ray polarization from the X-ray-bright filament. G0.13-0.11 in the Galactic center (GC) region. This filament features a bright, hard X-ray source that is most plausibly a pulsar wind nebula (PWN) and an extended and structured diffuse component. Combining the polarization signal from IXPE with the imaging/spectroscopic data from Chandra, we find that X-ray emission of G0.13-0.11 is highly polarized PD=$57(\pm18)$% in the 3-6 keV band, while the polarization angle is PA=$21^\circ(\pm9^\circ)$. This high degree of polarization proves the synchrotron origin of the X-ray emission from G0.13-0.11. In turn, the measured polarization angle implies that the X-ray emission is polarized approximately perpendicular to a sequence of nonthermal radio filaments that may be part of the GC Radio Arc. The magnetic field on the order of $100\,{\rm渭G}$ appears to be preferentially ordered along the filaments. The above field strength is the fiducial value that makes our model self-consistent, while the other conclusions are largely model independent. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.04421v2-abstract-full').style.display = 'none'; document.getElementById('2312.04421v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 7 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in 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 686, A14 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2311.04632">arXiv:2311.04632</a> <span> [<a href="https://arxiv.org/pdf/2311.04632">pdf</a>, <a href="https://arxiv.org/format/2311.04632">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/ad1832">10.3847/2041-8213/ad1832 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> X-Ray Polarized View on the Accretion Geometry in the X-Ray Binary Circinus X-1 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Rankin%2C+J">John Rankin</a>, <a href="/search/astro-ph?searchtype=author&query=La+Monaca%2C+F">Fabio La Monaca</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Bobrikova%2C+A">Anna Bobrikova</a>, <a href="/search/astro-ph?searchtype=author&query=Kravtsov%2C+V">Vadim Kravtsov</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Pilia%2C+M">Maura Pilia</a>, <a href="/search/astro-ph?searchtype=author&query=Veledina%2C+A">Alexandra Veledina</a>, <a href="/search/astro-ph?searchtype=author&query=Fender%2C+R">Rob Fender</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">Philip Kaaret</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Marinucci%2C+A">Andrea Marinucci</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Papitto%2C+A">Alessandro Papitto</a>, <a href="/search/astro-ph?searchtype=author&query=Tennant%2C+A+F">Allyn F. Tennant</a>, <a href="/search/astro-ph?searchtype=author&query=Tsygankov%2C+S+S">Sergey S. Tsygankov</a>, <a href="/search/astro-ph?searchtype=author&query=Weisskopf%2C+M+C">Martin C. Weisskopf</a>, <a href="/search/astro-ph?searchtype=author&query=Wu%2C+K">Kinwah Wu</a>, <a href="/search/astro-ph?searchtype=author&query=Zane%2C+S">Silvia Zane</a>, <a href="/search/astro-ph?searchtype=author&query=Ambrosino%2C+F">Filippo Ambrosino</a>, <a href="/search/astro-ph?searchtype=author&query=Farinelli%2C+R">Ruben Farinelli</a>, <a href="/search/astro-ph?searchtype=author&query=Gnarini%2C+A">Andrea Gnarini</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Antonelli%2C+L+A">Lucio A. Antonelli</a> , et al. (79 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2311.04632v2-abstract-short" style="display: inline;"> Cir X-1 is a neutron star X-ray binary characterized by strong variations in flux during its eccentric $\sim$16.6 days orbit. There are also strong variations in the spectral state, and historically it has shown both atoll and Z state properties. We observed the source with the Imaging X-ray Polarimetry Explorer during two orbital segments, 6 days apart, for a total of 263~ks. We find an X-ray pol… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.04632v2-abstract-full').style.display = 'inline'; document.getElementById('2311.04632v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.04632v2-abstract-full" style="display: none;"> Cir X-1 is a neutron star X-ray binary characterized by strong variations in flux during its eccentric $\sim$16.6 days orbit. There are also strong variations in the spectral state, and historically it has shown both atoll and Z state properties. We observed the source with the Imaging X-ray Polarimetry Explorer during two orbital segments, 6 days apart, for a total of 263~ks. We find an X-ray polarization degree in these segments of $1.6\%\pm0.3\%$ and $1.4\%\pm0.3\%$ at polarization angles of $37^\circ\pm5^\circ$ and $-12^\circ\pm7^\circ$, respectively. Thus we observed a rotation of the polarization angle by $49^\circ\pm8^\circ$ along the orbit. Because variations of accretion flow, and then of the hardness ratio, are expected during the orbit, we also studied the polarization binned in hardness ratio, and found the polarization angle differing by $67^\circ\pm11^\circ$ between the lowest and highest values of the hardness ratio. We discuss possible interpretations of this result that could indicate a possible misalignment between the symmetry axes of the accretion disk and the Comptonizing region caused by the misalignment of the neutron star's angular momentum with respect to the orbital one. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.04632v2-abstract-full').style.display = 'none'; document.getElementById('2311.04632v2-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">v1</span> submitted 8 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 6 figures, Accepted for publication in ApJL</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJL 961 L8 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.11510">arXiv:2310.11510</a> <span> [<a href="https://arxiv.org/pdf/2310.11510">pdf</a>, <a href="https://arxiv.org/format/2310.11510">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Observations of Low and Intermediate Spectral Peak Blazars with the Imaging X-ray Polarimetry Explorer </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Lalla%2C+N">Niccolo Di Lalla</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Omodei%2C+N">Nicola Omodei</a>, <a href="/search/astro-ph?searchtype=author&query=Peirson%2C+A+L">Abel L. Peirson</a>, <a href="/search/astro-ph?searchtype=author&query=Perri%2C+M">Matteo Perri</a>, <a href="/search/astro-ph?searchtype=author&query=Puccetti%2C+S">Simonetta Puccetti</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Ivan Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">Giacomo Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Berdyugin%2C+A+V">Andrei V. Berdyugin</a>, <a href="/search/astro-ph?searchtype=author&query=Cavazzuti%2C+E">Elisabetta Cavazzuti</a>, <a href="/search/astro-ph?searchtype=author&query=Cavero%2C+N+R">Nicole Rodriguez Cavero</a>, <a href="/search/astro-ph?searchtype=author&query=Donnarumma%2C+I">Immacolata Donnarumma</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Jormanainen%2C+J">Jenni Jormanainen</a>, <a href="/search/astro-ph?searchtype=author&query=Krawczynski%2C+H">Henric Krawczynski</a>, <a href="/search/astro-ph?searchtype=author&query=Lindfors%2C+E">Elina Lindfors</a>, <a href="/search/astro-ph?searchtype=author&query=Marin%2C+F">Frederic Marin</a>, <a href="/search/astro-ph?searchtype=author&query=Massaro%2C+F">Francesco Massaro</a>, <a href="/search/astro-ph?searchtype=author&query=Pacciani%2C+L">Luigi Pacciani</a> , et al. (133 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2310.11510v2-abstract-short" style="display: inline;"> We present X-ray polarimetry observations from the Imaging X-ray Polarimetry Explorer (IXPE) of three low spectral peak and one intermediate spectral peak blazars, namely 3C 273, 3C 279, 3C 454.3, and S5 0716+714. For none of these objects was IXPE able to detect X-ray polarization at the 3$蟽$ level. However, we placed upper limits on the polarization degree at $\sim$10-30\%. The undetected polari… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.11510v2-abstract-full').style.display = 'inline'; document.getElementById('2310.11510v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.11510v2-abstract-full" style="display: none;"> We present X-ray polarimetry observations from the Imaging X-ray Polarimetry Explorer (IXPE) of three low spectral peak and one intermediate spectral peak blazars, namely 3C 273, 3C 279, 3C 454.3, and S5 0716+714. For none of these objects was IXPE able to detect X-ray polarization at the 3$蟽$ level. However, we placed upper limits on the polarization degree at $\sim$10-30\%. The undetected polarizations favor models where the X-ray band is dominated by unpolarized photons upscattered by relativistic electrons in the jets of blazars, although hadronic models are not completely eliminated. We discuss the X-ray polarization upper limits in the context of our contemporaneous multiwavelength polarization campaigns. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.11510v2-abstract-full').style.display = 'none'; document.getElementById('2310.11510v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 10 figures, 6 tables; submitted to the Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.06097">arXiv:2310.06097</a> <span> [<a href="https://arxiv.org/pdf/2310.06097">pdf</a>, <a href="https://arxiv.org/format/2310.06097">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/10.1051/0004-6361/202347408">10.1051/0004-6361/202347408 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Magnetic Field Properties inside the Jet of Mrk 421: Multiwavelength Polarimetry Including the Imaging X-ray Polarimetry Explorer </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Midde%2C+R">Riccardo Midde</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Pacciani%2C+L">Luigi Pacciani</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Tavecchio%2C+F">Fabrizio Tavecchio</a>, <a href="/search/astro-ph?searchtype=author&query=Cibrario%2C+N">Nicol貌 Cibrario</a>, <a href="/search/astro-ph?searchtype=author&query=Tugliani%2C+S">Stefano Tugliani</a>, <a href="/search/astro-ph?searchtype=author&query=Bonino%2C+R">Raffaella Bonino</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Puccetti%2C+S">Simonetta Puccetti</a>, <a href="/search/astro-ph?searchtype=author&query=Tombesi%2C+F">Francesco Tombesi</a>, <a href="/search/astro-ph?searchtype=author&query=Costa%2C+E">Enrico Costa</a>, <a href="/search/astro-ph?searchtype=author&query=Donnarumma%2C+I">Immacolata Donnarumma</a>, <a href="/search/astro-ph?searchtype=author&query=Soffitta%2C+P">Paolo Soffitta</a>, <a href="/search/astro-ph?searchtype=author&query=Mizuno%2C+T">Tsunefumi Mizuno</a>, <a href="/search/astro-ph?searchtype=author&query=Fukazawa%2C+Y">Yasushi Fukazawa</a>, <a href="/search/astro-ph?searchtype=author&query=Kawabata%2C+K+S">Koji S. Kawabata</a>, <a href="/search/astro-ph?searchtype=author&query=Nakaoka%2C+T">Tatsuya Nakaoka</a>, <a href="/search/astro-ph?searchtype=author&query=Uemura%2C+M">Makoto Uemura</a>, <a href="/search/astro-ph?searchtype=author&query=Imazawa%2C+R">Ryo Imazawa</a> , et al. (111 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2310.06097v1-abstract-short" style="display: inline;"> We conducted a polarimetry campaign from radio to X-ray wavelengths of the high-synchrotron-peak (HSP) blazar Mrk 421, including Imaging X-ray Polarimetry Explorer (IXPE) measurements on 2022 December 6-8. We detected X-ray polarization of Mrk 421 with a degree of $螤_{\rm X}$=14$\pm$1$\%$ and an electric-vector position angle $蠄_{\rm X}$=107$\pm$3$^{\circ}$ in the 2-8 keV band. From the time varia… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.06097v1-abstract-full').style.display = 'inline'; document.getElementById('2310.06097v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.06097v1-abstract-full" style="display: none;"> We conducted a polarimetry campaign from radio to X-ray wavelengths of the high-synchrotron-peak (HSP) blazar Mrk 421, including Imaging X-ray Polarimetry Explorer (IXPE) measurements on 2022 December 6-8. We detected X-ray polarization of Mrk 421 with a degree of $螤_{\rm X}$=14$\pm$1$\%$ and an electric-vector position angle $蠄_{\rm X}$=107$\pm$3$^{\circ}$ in the 2-8 keV band. From the time variability analysis, we find a significant episodic variation in $蠄_{\rm X}$. During 7 months from the first IXPE pointing of Mrk 421 in 2022 May, $蠄_{\rm X}$ varied across the range of 0$^{\circ}$ to 180$^{\circ}$, while $螤_{\rm X}$ maintained similar values within $\sim$10-15$\%$. Furthermore, a swing in $蠄_{\rm X}$ in 2022 June was accompanied by simultaneous spectral variations. The results of the multiwavelength polarimetry show that the X-ray polarization degree was generally $\sim$2-3 times greater than that at longer wavelengths, while the polarization angle fluctuated. Additionally, based on radio, infrared, and optical polarimetry, we find that rotation of $蠄$ occurred in the opposite direction with respect to the rotation of $蠄_{\rm X}$ over longer timescales at similar epochs. The polarization behavior observed across multiple wavelengths is consistent with previous IXPE findings for HSP blazars. This result favors the energy-stratified shock model developed to explain variable emission in relativistic jets. The accompanying spectral variation during the $蠄_{\rm X}$ rotation can be explained by a fluctuation in the physical conditions, e.g., in the energy distribution of relativistic electrons. The opposite rotation direction of $蠄$ between the X-ray and longer-wavelength polarization accentuates the conclusion that the X-ray emitting region is spatially separated from that at longer wavelengths. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.06097v1-abstract-full').style.display = 'none'; document.getElementById('2310.06097v1-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, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">17 pages, 13 figures, 4 tables; Accepted for publication in A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 681, A12 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2309.17206">arXiv:2309.17206</a> <span> [<a href="https://arxiv.org/pdf/2309.17206">pdf</a>, <a href="https://arxiv.org/format/2309.17206">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> </div> <p class="title is-5 mathjax"> The future of X-ray polarimetry towards the 3-Dimensional photoelectron track reconstruction </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Soffitta%2C+P">Paolo Soffitta</a>, <a href="/search/astro-ph?searchtype=author&query=Costa%2C+E">Enrico Costa</a>, <a href="/search/astro-ph?searchtype=author&query=Fabiani%2C+S">Sergio Fabiani</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Ratheesh%2C+A">Ajay Ratheesh</a>, <a href="/search/astro-ph?searchtype=author&query=La+Monaca%2C+F">Fabio La Monaca</a>, <a href="/search/astro-ph?searchtype=author&query=Rankin%2C+J">John Rankin</a>, <a href="/search/astro-ph?searchtype=author&query=Del+Monte%2C+E">Ettore Del Monte</a>, <a href="/search/astro-ph?searchtype=author&query=Rubini%2C+A">Alda Rubini</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="2309.17206v1-abstract-short" style="display: inline;"> The development of the first X-ray polarimeter, based on the photoelectric effect 20 years ago and implemented thanks to advances in gas amplification structures and readout techniques, had a significant impact in opening a new window for X-ray polarimetry. This system measures the X-ray polarization by reconstructing the initial direction of the photoelectron, emitted by the interaction of an inc… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.17206v1-abstract-full').style.display = 'inline'; document.getElementById('2309.17206v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.17206v1-abstract-full" style="display: none;"> The development of the first X-ray polarimeter, based on the photoelectric effect 20 years ago and implemented thanks to advances in gas amplification structures and readout techniques, had a significant impact in opening a new window for X-ray polarimetry. This system measures the X-ray polarization by reconstructing the initial direction of the photoelectron, emitted by the interaction of an incident photon with an atomic electron, in a gas mixture from an ionization track collected on a two-dimensional plane. However, actual X-ray polarimeters, are still requiring relatively long exposure time and cannot coupled with high effective area mirrors or concentrators. In this context, the high yield polarimetry experiment in X-rays (Hype-X) project is currently underway, aiming to improve the sensitivity of the next generation X-ray polarimetry detectors taking advantage of the recent advancements in imaging techniques for high-resolution time projection chambers. In particular, we are evaluating the use of TIMEPIX3 to be applied for the read-out of a gas detector, which will allow us to obtain a three-dimensional image of the photoelectron track. To evaluate the improvement achievable by using a 3D track reconstruction, in this paper, we have reproduced a three-dimensional photoelectron track from a 'Geant4' Monte Carlo simulation and examined the sensitivity of X-ray polarimetry using a new three-dimensional track reconstruction algorithm. We report the improvement of the modulation factor with three-dimensional track reconstruction as $\sim5\%$ (relative) in the 2-8 keV range and $\sim17\%$ (relative) in the 2-4 keV range compared to the current two-dimensional polarimetry system. This is equivalent to add a further telescope to the three-telescope systems now employed in space on board the IXPE mission. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.17206v1-abstract-full').style.display = 'none'; document.getElementById('2309.17206v1-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, 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">8 pages, 4 Figures, 1 Table; Submitted to Journal of Instrumentation (JINST). Proceedings of the 24th International Workshop on Radiation Imaging Detectors (iWoRiD) 2023</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2309.16067">arXiv:2309.16067</a> <span> [<a href="https://arxiv.org/pdf/2309.16067">pdf</a>, <a href="https://arxiv.org/format/2309.16067">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 Polarized Cosmic Hand: IXPE Observations of PSR B1509-58/MSH 15-52 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Romani%2C+R+W">Roger W. Romani</a>, <a href="/search/astro-ph?searchtype=author&query=Wong%2C+J">Josephine Wong</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Lalla%2C+N">Niccolo Di Lalla</a>, <a href="/search/astro-ph?searchtype=author&query=Omodei%2C+N">Nicola Omodei</a>, <a href="/search/astro-ph?searchtype=author&query=Xie%2C+F">Fei Xie</a>, <a href="/search/astro-ph?searchtype=author&query=Ng%2C+C+-">C. -Y. Ng</a>, <a href="/search/astro-ph?searchtype=author&query=Ferrazzoli%2C+R">Riccardo Ferrazzoli</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Bucciantini%2C+N">Niccolo Bucciantini</a>, <a href="/search/astro-ph?searchtype=author&query=Pilia%2C+M">Maura Pilia</a>, <a href="/search/astro-ph?searchtype=author&query=Slane%2C+P">Patrick Slane</a>, <a href="/search/astro-ph?searchtype=author&query=Weisskopf%2C+M+C">Martin C. Weisskopf</a>, <a href="/search/astro-ph?searchtype=author&query=Johnston%2C+S">Simon Johnston</a>, <a href="/search/astro-ph?searchtype=author&query=Burgay%2C+M">Marta Burgay</a>, <a href="/search/astro-ph?searchtype=author&query=Wei%2C+D">Deng Wei</a>, <a href="/search/astro-ph?searchtype=author&query=Yang%2C+Y">Yi-Jung Yang</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+S">Shumeng Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Antonelli%2C+L+A">Lucio A. Antonelli</a>, <a href="/search/astro-ph?searchtype=author&query=Bachetti%2C+M">Matteo Bachetti</a>, <a href="/search/astro-ph?searchtype=author&query=Baldini%2C+L">Luca Baldini</a>, <a href="/search/astro-ph?searchtype=author&query=Baumgartner%2C+W+H">Wayne H. Baumgartner</a>, <a href="/search/astro-ph?searchtype=author&query=Bellazzini%2C+R">Ronaldo Bellazzini</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">Stefano Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Bongiorno%2C+S+D">Stephen D. Bongiorno</a>, <a href="/search/astro-ph?searchtype=author&query=Bonino%2C+R">Raffaella Bonino</a> , et al. (78 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="2309.16067v1-abstract-short" style="display: inline;"> We describe IXPE polarization observations of the Pulsar Wind Nebula (PWN) MSH15-52, the `Cosmic Hand'. We find X-ray polarization across the PWN, with B field vectors generally aligned with filamentary X-ray structures. High significance polarization is seen in arcs surrounding the pulsar and toward the end of the `jet', with polarization degree PD>70%, thus approaching the maximum allowed synchr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.16067v1-abstract-full').style.display = 'inline'; document.getElementById('2309.16067v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.16067v1-abstract-full" style="display: none;"> We describe IXPE polarization observations of the Pulsar Wind Nebula (PWN) MSH15-52, the `Cosmic Hand'. We find X-ray polarization across the PWN, with B field vectors generally aligned with filamentary X-ray structures. High significance polarization is seen in arcs surrounding the pulsar and toward the end of the `jet', with polarization degree PD>70%, thus approaching the maximum allowed synchrotron value. In contrast, the base of the jet has lower polarization, indicating a complex magnetic field at significant angle to the jet axis. We also detect significant polarization from PSR B1509-58 itself. Although only the central pulse-phase bin of the pulse has high individual significance, flanking bins provide lower significance detections and, in conjunction with the X-ray image and radio polarization, can be used to constrain rotating vector model solutions for the pulsar geometry. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.16067v1-abstract-full').style.display = 'none'; document.getElementById('2309.16067v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 September, 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">To appear in the Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2309.01879">arXiv:2309.01879</a> <span> [<a href="https://arxiv.org/pdf/2309.01879">pdf</a>, <a href="https://arxiv.org/format/2309.01879">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"> Magnetic structures and turbulence in SN 1006 revealed with imaging X-ray polarimetry </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Zhou%2C+P">Ping Zhou</a>, <a href="/search/astro-ph?searchtype=author&query=Prokhorov%2C+D">Dmitry Prokhorov</a>, <a href="/search/astro-ph?searchtype=author&query=Ferrazzoli%2C+R">Riccardo Ferrazzoli</a>, <a href="/search/astro-ph?searchtype=author&query=Yang%2C+Y">Yi-Jung Yang</a>, <a href="/search/astro-ph?searchtype=author&query=Slane%2C+P">Patrick Slane</a>, <a href="/search/astro-ph?searchtype=author&query=Vink%2C+J">Jacco Vink</a>, <a href="/search/astro-ph?searchtype=author&query=Silvestri%2C+S">Stefano Silvestri</a>, <a href="/search/astro-ph?searchtype=author&query=Bucciantini%2C+N">Niccol貌 Bucciantini</a>, <a href="/search/astro-ph?searchtype=author&query=Reynoso%2C+E">Estela Reynoso</a>, <a href="/search/astro-ph?searchtype=author&query=Moffett%2C+D">David Moffett</a>, <a href="/search/astro-ph?searchtype=author&query=Soffitta%2C+P">Paolo Soffitta</a>, <a href="/search/astro-ph?searchtype=author&query=Swartz%2C+D">Doug Swartz</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">Philip Kaaret</a>, <a href="/search/astro-ph?searchtype=author&query=Baldini%2C+L">Luca Baldini</a>, <a href="/search/astro-ph?searchtype=author&query=Costa%2C+E">Enrico Costa</a>, <a href="/search/astro-ph?searchtype=author&query=Ng%2C+C+-">C. -Y. Ng</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">Victor Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Ehlert%2C+S+R">Steven R. Ehlert</a>, <a href="/search/astro-ph?searchtype=author&query=Heyl%2C+J">Jeremy Heyl</a>, <a href="/search/astro-ph?searchtype=author&query=Marin%2C+F">Fr茅d茅ric Marin</a>, <a href="/search/astro-ph?searchtype=author&query=Mizuno%2C+T">Tsunefumi Mizuno</a>, <a href="/search/astro-ph?searchtype=author&query=Pesce-Rollins%2C+M">Melissa Pesce-Rollins</a>, <a href="/search/astro-ph?searchtype=author&query=Sgr%C3%B2%2C+C">Carmelo Sgr貌</a>, <a href="/search/astro-ph?searchtype=author&query=Tamagawa%2C+T">Toru Tamagawa</a> , et al. (77 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="2309.01879v1-abstract-short" style="display: inline;"> Young supernova remnants (SNRs) strongly modify surrounding magnetic fields, which in turn play an essential role in accelerating cosmic rays (CRs). X-ray polarization measurements probe magnetic field morphology and turbulence at the immediate acceleration site. We report the X-ray polarization distribution in the northeastern shell of SN1006 from a 1 Ms observation with the Imaging X-ray Polarim… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.01879v1-abstract-full').style.display = 'inline'; document.getElementById('2309.01879v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.01879v1-abstract-full" style="display: none;"> Young supernova remnants (SNRs) strongly modify surrounding magnetic fields, which in turn play an essential role in accelerating cosmic rays (CRs). X-ray polarization measurements probe magnetic field morphology and turbulence at the immediate acceleration site. We report the X-ray polarization distribution in the northeastern shell of SN1006 from a 1 Ms observation with the Imaging X-ray Polarimetry Explorer (IXPE). We found an average polarization degree of $22.4\pm 3.5\%$ and an average polarization angle of $-45.4\pm 4.5^\circ$ (measured on the plane of the sky from north to east). The X-ray polarization angle distribution reveals that the magnetic fields immediately behind the shock in the northeastern shell of SN 1006 are nearly parallel to the shock normal or radially distributed, similar to that in the radio observations, and consistent with the quasi-parallel CR acceleration scenario. The X-ray emission is marginally more polarized than that in the radio band. The X-ray polarization degree of SN 1006 is much larger than that in Cas A and Tycho, together with the relatively tenuous and smooth ambient medium of the remnant, favoring that CR-induced instabilities set the turbulence in SN 1006 and CR acceleration is environment-dependent. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.01879v1-abstract-full').style.display = 'none'; document.getElementById('2309.01879v1-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 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">15 pages, 4 Figures, 2 Tables; accepted for publication in The Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.00039">arXiv:2308.00039</a> <span> [<a href="https://arxiv.org/pdf/2308.00039">pdf</a>, <a href="https://arxiv.org/format/2308.00039">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> IXPE and multi-wavelength observations of blazar PG 1553+113 reveal an orphan optical polarization swing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Perri%2C+M">Matteo Perri</a>, <a href="/search/astro-ph?searchtype=author&query=Puccetti%2C+S">Simonetta Puccetti</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Cavero%2C+N+R">Nicole Rodriguez Cavero</a>, <a href="/search/astro-ph?searchtype=author&query=Tavecchio%2C+F">Fabrizio Tavecchio</a>, <a href="/search/astro-ph?searchtype=author&query=Donnarumma%2C+I">Immacolata Donnarumma</a>, <a href="/search/astro-ph?searchtype=author&query=Laurenti%2C+M">Marco Laurenti</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Pacciani%2C+L">Luigi Pacciani</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Aceituno%2C+F+J">Francisco Jos茅 Aceituno</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">Giacomo Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Casanova%2C+V">V铆ctor Casanova</a>, <a href="/search/astro-ph?searchtype=author&query=Ag%C3%ADs-Gonz%C3%A1lez%2C+B">Beatriz Ag铆s-Gonz谩lez</a>, <a href="/search/astro-ph?searchtype=author&query=Sota%2C+A">Alfredo Sota</a>, <a href="/search/astro-ph?searchtype=author&query=Casadio%2C+C">Carolina Casadio</a>, <a href="/search/astro-ph?searchtype=author&query=Escudero%2C+J">Juan Escudero</a>, <a href="/search/astro-ph?searchtype=author&query=Myserlis%2C+I">Ioannis Myserlis</a>, <a href="/search/astro-ph?searchtype=author&query=Sievers%2C+A">Albrecht Sievers</a>, <a href="/search/astro-ph?searchtype=author&query=Kouch%2C+P+M">Pouya M. Kouch</a> , et al. (97 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2308.00039v1-abstract-short" style="display: inline;"> The lower energy peak of the spectral energy distribution of blazars has commonly been ascribed to synchrotron radiation from relativistic particles in the jets. Despite the consensus regarding jet emission processes, the particle acceleration mechanism is still debated. Here, we present the first X-ray polarization observations of PG 1553+113, a high-synchrotron-peak blazar observed by the Imagin… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.00039v1-abstract-full').style.display = 'inline'; document.getElementById('2308.00039v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.00039v1-abstract-full" style="display: none;"> The lower energy peak of the spectral energy distribution of blazars has commonly been ascribed to synchrotron radiation from relativistic particles in the jets. Despite the consensus regarding jet emission processes, the particle acceleration mechanism is still debated. Here, we present the first X-ray polarization observations of PG 1553+113, a high-synchrotron-peak blazar observed by the Imaging X-ray Polarimetry Explorer (IXPE). We detect an X-ray polarization degree of $(10\pm2)\%$ along an electric-vector position angle of $蠄_X=86^{\circ}\pm8^{\circ}$. At the same time, the radio and optical polarization degrees are lower by a factor of $\sim$3. During our IXPE pointing, we observed the first orphan optical polarization swing of the IXPE era, as the optical angle of PG 1553+113 underwent a smooth monotonic rotation by about 125$^\circ$, with a rate of $\sim$17 degrees per day. We do not find evidence of a similar rotation in either radio or X-rays, which suggests that the X-ray and optically emitting regions are separate or, at most, partially co-spatial. Our spectro-polarimetric results provide further evidence that the steady-state X-ray emission in blazars originates in a shock-accelerated and energy-stratified electron population. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.00039v1-abstract-full').style.display = 'none'; document.getElementById('2308.00039v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 31 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for pubblication in The Astrophysical Journal Letters. 3 Figures, 13 pages</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.13898">arXiv:2305.13898</a> <span> [<a href="https://arxiv.org/pdf/2305.13898">pdf</a>, <a href="https://arxiv.org/format/2305.13898">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/2041-8213/acd242">10.3847/2041-8213/acd242 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> X-ray Polarization of BL Lacertae in Outburst </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Peirson%2C+A+L">Abel L. Peirson</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Pacciani%2C+L">Luigi Pacciani</a>, <a href="/search/astro-ph?searchtype=author&query=Romani%2C+R+W">Roger W. Romani</a>, <a href="/search/astro-ph?searchtype=author&query=Wu%2C+K">Kinwah Wu</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Lalla%2C+N">Niccolo Di Lalla</a>, <a href="/search/astro-ph?searchtype=author&query=Omodei%2C+N">Nicola Omodei</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Ivan Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Kouch%2C+P+M">Pouya M. Kouch</a>, <a href="/search/astro-ph?searchtype=author&query=Lindfors%2C+E">Elina Lindfors</a>, <a href="/search/astro-ph?searchtype=author&query=Aceituno%2C+F+J">Francisco Jose Aceituno</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardos%2C+M+I">Maria I. Bernardos</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">Giacomo Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Casanova%2C+V">Victor Casanova</a>, <a href="/search/astro-ph?searchtype=author&query=Garcia-Comas%2C+M">Maya Garcia-Comas</a>, <a href="/search/astro-ph?searchtype=author&query=Agis-Gonzalez%2C+B">Beatriz Agis-Gonzalez</a>, <a href="/search/astro-ph?searchtype=author&query=Husillos%2C+C">Cesar Husillos</a>, <a href="/search/astro-ph?searchtype=author&query=Marchini%2C+A">Alessandro Marchini</a> , et al. (106 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.13898v2-abstract-short" style="display: inline;"> We report the first $> 99\%$ confidence detection of X-ray polarization in BL Lacertae. During a recent X-ray/$纬$-ray outburst, a 287 ksec observation (2022 November 27-30) was taken using the Imaging X-ray Polarimetry Explorer ({\it IXPE}), together with contemporaneous multiwavelength observations from the Neil Gehrels {\it Swift} observatory and {\it XMM-Newton} in soft X-rays (0.3--10~keV), {\… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.13898v2-abstract-full').style.display = 'inline'; document.getElementById('2305.13898v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.13898v2-abstract-full" style="display: none;"> We report the first $> 99\%$ confidence detection of X-ray polarization in BL Lacertae. During a recent X-ray/$纬$-ray outburst, a 287 ksec observation (2022 November 27-30) was taken using the Imaging X-ray Polarimetry Explorer ({\it IXPE}), together with contemporaneous multiwavelength observations from the Neil Gehrels {\it Swift} observatory and {\it XMM-Newton} in soft X-rays (0.3--10~keV), {\it NuSTAR} in hard X-rays (3--70~keV), and optical polarization from the Calar Alto, and Perkins Telescope observatories. Our contemporaneous X-ray data suggest that the {\it IXPE} energy band is at the crossover between the low- and high-frequency blazar emission humps. The source displays significant variability during the observation, and we measure polarization in three separate time bins. Contemporaneous X-ray spectra allow us to determine the relative contribution from each emission hump. We find $>99\%$ confidence X-ray polarization $螤_{2-4{\rm keV}} = 21.7^{+5.6}_{-7.9}\%$ and electric vector polarization angle $蠄_{2-4{\rm keV}} = -28.7 \pm 8.7^{\circ}$ in the time bin with highest estimated synchrotron flux contribution. We discuss possible implications of our observations, including previous {\it IXPE} BL Lacertae pointings, tentatively concluding that synchrotron self-Compton emission dominates over hadronic emission processes during the observed epochs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.13898v2-abstract-full').style.display = 'none'; document.getElementById('2305.13898v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted to ApJL. 16 pages, 8 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.13497">arXiv:2305.13497</a> <span> [<a href="https://arxiv.org/pdf/2305.13497">pdf</a>, <a href="https://arxiv.org/format/2305.13497">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Discovery of X-ray polarization angle rotation in active galaxy Mrk 421 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Ehlert%2C+S+R">Steven R. Ehlert</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Donnarumma%2C+I">Immacolata Donnarumma</a>, <a href="/search/astro-ph?searchtype=author&query=Tavecchio%2C+F">Fabrizio Tavecchio</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Kiehlmann%2C+S">Sebastian Kiehlmann</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Puccetti%2C+S">Simonetta Puccetti</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Perri%2C+M">Matteo Perri</a>, <a href="/search/astro-ph?searchtype=author&query=Pacciani%2C+L">Luigi Pacciani</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Romani%2C+R+W">Roger W. Romani</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D">Dmitry Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Bourbah%2C+I+G">Ioakeim G. Bourbah</a>, <a href="/search/astro-ph?searchtype=author&query=Kontopodis%2C+E">Evangelos Kontopodis</a>, <a href="/search/astro-ph?searchtype=author&query=Mandarakas%2C+N">Nikos Mandarakas</a>, <a href="/search/astro-ph?searchtype=author&query=Romanopoulos%2C+S">Stylianos Romanopoulos</a>, <a href="/search/astro-ph?searchtype=author&query=Skalidis%2C+R">Raphael Skalidis</a> , et al. (118 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.13497v1-abstract-short" style="display: inline;"> The magnetic field conditions in astrophysical relativistic jets can be probed by multiwavelength polarimetry, which has been recently extended to X-rays. For example, one can track how the magnetic field changes in the flow of the radiating particles by observing rotations of the electric vector position angle $唯$. Here we report the discovery of a $唯_{\mathrm x}$ rotation in the X-ray band in th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.13497v1-abstract-full').style.display = 'inline'; document.getElementById('2305.13497v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.13497v1-abstract-full" style="display: none;"> The magnetic field conditions in astrophysical relativistic jets can be probed by multiwavelength polarimetry, which has been recently extended to X-rays. For example, one can track how the magnetic field changes in the flow of the radiating particles by observing rotations of the electric vector position angle $唯$. Here we report the discovery of a $唯_{\mathrm x}$ rotation in the X-ray band in the blazar Mrk 421 at an average flux state. Across the 5 days of Imaging X-ray Polarimetry Explorer (IXPE) observations of 4-6 and 7-9 June 2022, $唯_{\mathrm x}$ rotated in total by $\geq360^\circ$. Over the two respective date ranges, we find constant, within uncertainties, rotation rates ($80 \pm 9$ and $91 \pm 8 ^\circ/\rm day$) and polarization degrees ($螤_{\mathrm x}=10\%\pm1\%$). Simulations of a random walk of the polarization vector indicate that it is unlikely that such rotation(s) are produced by a stochastic process. The X-ray emitting site does not completely overlap the radio/infrared/optical emission sites, as no similar rotation of $唯$ was observed in quasi-simultaneous data at longer wavelengths. We propose that the observed rotation was caused by a helical magnetic structure in the jet, illuminated in the X-rays by a localized shock propagating along this helix. The optically emitting region likely lies in a sheath surrounding an inner spine where the X-ray radiation is released. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.13497v1-abstract-full').style.display = 'none'; document.getElementById('2305.13497v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.13028">arXiv:2305.13028</a> <span> [<a href="https://arxiv.org/pdf/2305.13028">pdf</a>, <a href="https://arxiv.org/format/2305.13028">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 X-ray polarisation of the Seyfert 1 galaxy IC 4329A </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ingram%2C+A">A. Ingram</a>, <a href="/search/astro-ph?searchtype=author&query=Ewing%2C+M">M. Ewing</a>, <a href="/search/astro-ph?searchtype=author&query=Marinucci%2C+A">A. Marinucci</a>, <a href="/search/astro-ph?searchtype=author&query=Tagliacozzo%2C+D">D. Tagliacozzo</a>, <a href="/search/astro-ph?searchtype=author&query=Rosario%2C+D+J">D. J. Rosario</a>, <a href="/search/astro-ph?searchtype=author&query=Veledina%2C+A">A. Veledina</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">D. E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Marin%2C+F">F. Marin</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">S. Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">J. Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Matt%2C+G">G. Matt</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">H. L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Ursini%2C+F">F. Ursini</a>, <a href="/search/astro-ph?searchtype=author&query=De+Rosa%2C+A">A. De Rosa</a>, <a href="/search/astro-ph?searchtype=author&query=Petrucci%2C+P">P-O. Petrucci</a>, <a href="/search/astro-ph?searchtype=author&query=Madejski%2C+G">G. Madejski</a>, <a href="/search/astro-ph?searchtype=author&query=Barnouin%2C+T">T. Barnouin</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">L. Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Dovvciak%2C+M">M. Dovvciak</a>, <a href="/search/astro-ph?searchtype=author&query=Gianolli%2C+V+E">V. E. Gianolli</a>, <a href="/search/astro-ph?searchtype=author&query=Krawczynski%2C+H">H. Krawczynski</a>, <a href="/search/astro-ph?searchtype=author&query=Loktev%2C+V">V. Loktev</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">R. Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Podgorny%2C+J">J. Podgorny</a>, <a href="/search/astro-ph?searchtype=author&query=Puccetti%2C+S">S. Puccetti</a> , et al. (83 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.13028v2-abstract-short" style="display: inline;"> We present an X-ray spectro-polarimetric analysis of the bright Seyfert galaxy IC 4329A. The Imaging X-ray Polarimetry Explorer (IXPE) observed the source for ~500 ks, supported by XMM-Newton (~60 ks) and NuSTAR (~80 ks) exposures. We detect polarisation in the 2-8 keV band with 2.97 sigma confidence. We report a polarisation degree of $3.3\pm1.1$ per cent and a polarisation angle of $78\pm10$ deg… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.13028v2-abstract-full').style.display = 'inline'; document.getElementById('2305.13028v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.13028v2-abstract-full" style="display: none;"> We present an X-ray spectro-polarimetric analysis of the bright Seyfert galaxy IC 4329A. The Imaging X-ray Polarimetry Explorer (IXPE) observed the source for ~500 ks, supported by XMM-Newton (~60 ks) and NuSTAR (~80 ks) exposures. We detect polarisation in the 2-8 keV band with 2.97 sigma confidence. We report a polarisation degree of $3.3\pm1.1$ per cent and a polarisation angle of $78\pm10$ degrees (errors are 1 sigma confidence). The X-ray polarisation is consistent with being aligned with the radio jet, albeit partially due to large uncertainties on the radio position angle. We jointly fit the spectra from the three observatories to constrain the presence of a relativistic reflection component. From this, we obtain constraints on the inclination angle to the inner disc (< 39 degrees at 99 per cent confidence) and the disc inner radius (< 11 gravitational radii at 99 per cent confidence), although we note that modelling systematics in practice add to the quoted statistical error. Our spectro-polarimetric modelling indicates that the 2-8 keV polarisation is consistent with being dominated by emission directly observed from the X-ray corona, but the polarisation of the reflection component is completely unconstrained. Our constraints on viewer inclination and polarisation degree tentatively favour more asymmetric, possibly out-flowing, coronal geometries that produce more highly polarised emission, but the coronal geometry is unconstrained at the 3 sigma level. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.13028v2-abstract-full').style.display = 'none'; document.getElementById('2305.13028v2-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 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted for publication in MNRAS, 13 pages, 9 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.10213">arXiv:2305.10213</a> <span> [<a href="https://arxiv.org/pdf/2305.10213">pdf</a>, <a href="https://arxiv.org/format/2305.10213">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 geometry of the hot corona in MCG-05-23-16 constrained by X-ray polarimetry </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Tagliacozzo%2C+D">D. Tagliacozzo</a>, <a href="/search/astro-ph?searchtype=author&query=Marinucci%2C+A">A. Marinucci</a>, <a href="/search/astro-ph?searchtype=author&query=Ursini%2C+F">F. Ursini</a>, <a href="/search/astro-ph?searchtype=author&query=Matt%2C+G">G. Matt</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">S. Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Baldini%2C+L">L. Baldini</a>, <a href="/search/astro-ph?searchtype=author&query=Barnouin%2C+T">T. Barnouin</a>, <a href="/search/astro-ph?searchtype=author&query=Rodriguez%2C+N+C">N. Cavero Rodriguez</a>, <a href="/search/astro-ph?searchtype=author&query=De+Rosa%2C+A">A. De Rosa</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">L. Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Dovciak%2C+M">M. Dovciak</a>, <a href="/search/astro-ph?searchtype=author&query=Harper%2C+D">D. Harper</a>, <a href="/search/astro-ph?searchtype=author&query=Ingram%2C+A">A. Ingram</a>, <a href="/search/astro-ph?searchtype=author&query=Karas%2C+V">V. Karas</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">D. E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Krawczynski%2C+H">H. Krawczynski</a>, <a href="/search/astro-ph?searchtype=author&query=Madejski%2C+G">G. Madejski</a>, <a href="/search/astro-ph?searchtype=author&query=Marin%2C+F">F. Marin</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">R. Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">H. L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">F. Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Panagiotou%2C+C">C. Panagiotou</a>, <a href="/search/astro-ph?searchtype=author&query=Petrucci%2C+P+O">P. O. Petrucci</a>, <a href="/search/astro-ph?searchtype=author&query=Podgorny%2C+J">J. Podgorny</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">J. Poutanen</a> , et al. (83 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.10213v1-abstract-short" style="display: inline;"> We report on the second observation of the radio-quiet active galactic nucleus (AGN) MCG-05-23-16 performed with the Imaging X-ray Polarimetry Explorer (IXPE). The observation started on 2022 November 6 for a net observing time of 640 ks, and was partly simultaneous with NuSTAR (86 ks). After combining these data with those obtained in the first IXPE pointing on May 2022 (simultaneous with XMM-New… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.10213v1-abstract-full').style.display = 'inline'; document.getElementById('2305.10213v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.10213v1-abstract-full" style="display: none;"> We report on the second observation of the radio-quiet active galactic nucleus (AGN) MCG-05-23-16 performed with the Imaging X-ray Polarimetry Explorer (IXPE). The observation started on 2022 November 6 for a net observing time of 640 ks, and was partly simultaneous with NuSTAR (86 ks). After combining these data with those obtained in the first IXPE pointing on May 2022 (simultaneous with XMM-Newton and NuSTAR) we find a 2-8 keV polarization degree $螤$ = 1.6 $\pm$ 0.7 (at 68 per cent confidence level), which corresponds to an upper limit $螤$ = 3.2 per cent (at 99 per cent confidence level). We then compare the polarization results with Monte Carlo simulations obtained with the MONK code, with which different coronal geometries have been explored (spherical lamppost, conical, slab and wedge). Furthermore, the allowed range of inclination angles is found for each geometry. If the best fit inclination value from a spectroscopic analysis is considered, a cone-shaped corona along the disc axis is disfavoured. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.10213v1-abstract-full').style.display = 'none'; document.getElementById('2305.10213v1-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 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 8 figures, 3 table. Submitted to MNRAS</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.12541">arXiv:2303.12541</a> <span> [<a href="https://arxiv.org/pdf/2303.12541">pdf</a>, <a href="https://arxiv.org/format/2303.12541">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/10.1093/mnras/stad1697">10.1093/mnras/stad1697 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Uncovering the geometry of the hot X-ray corona in the Seyfert galaxy NGC4151 with IXPE </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Gianolli%2C+V+E">V. E. Gianolli</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">D. E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">S. Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Ag%C3%ADs-Gonz%C3%A1lez%2C+B">B. Ag铆s-Gonz谩lez</a>, <a href="/search/astro-ph?searchtype=author&query=Madejski%2C+G">G. Madejski</a>, <a href="/search/astro-ph?searchtype=author&query=Marin%2C+F">F. Marin</a>, <a href="/search/astro-ph?searchtype=author&query=Marinucci%2C+A">A. Marinucci</a>, <a href="/search/astro-ph?searchtype=author&query=Matt%2C+G">G. Matt</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">R. Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Petrucci%2C+P">P-O. Petrucci</a>, <a href="/search/astro-ph?searchtype=author&query=Soffitta%2C+P">P. Soffitta</a>, <a href="/search/astro-ph?searchtype=author&query=Tagliacozzo%2C+D">D. Tagliacozzo</a>, <a href="/search/astro-ph?searchtype=author&query=Tombesi%2C+F">F. Tombesi</a>, <a href="/search/astro-ph?searchtype=author&query=Ursini%2C+F">F. Ursini</a>, <a href="/search/astro-ph?searchtype=author&query=Barnouin%2C+T">T. Barnouin</a>, <a href="/search/astro-ph?searchtype=author&query=De+Rosa%2C+A">A. De Rosa</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">L. Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Ingram%2C+A">A. Ingram</a>, <a href="/search/astro-ph?searchtype=author&query=Loktev%2C+V">V. Loktev</a>, <a href="/search/astro-ph?searchtype=author&query=Panagiotou%2C+C">C. Panagiotou</a>, <a href="/search/astro-ph?searchtype=author&query=Podgorny%2C+J">J. Podgorny</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">J. Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Puccetti%2C+S">S. Puccetti</a>, <a href="/search/astro-ph?searchtype=author&query=Ratheesh%2C+A">A. Ratheesh</a>, <a href="/search/astro-ph?searchtype=author&query=Veledina%2C+A">A. Veledina</a> , et al. (84 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="2303.12541v2-abstract-short" style="display: inline;"> We present an X-ray spectro-polarimetric analysis of the bright Seyfert galaxy NGC4151. The source has been observed with the Imaging X-ray Polarimetry Explorer (IXPE) for 700 ks, complemented with simultaneous XMM-Newton (50 ks) and NuSTAR (100 ks) pointings. A polarization degree $螤 = 4.9 {\pm} 1.1 \%$ and angle $唯= 86掳 {\pm} 7掳$ east of north ($68\%$ confidence level) are measured in the 2-8 ke… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.12541v2-abstract-full').style.display = 'inline'; document.getElementById('2303.12541v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.12541v2-abstract-full" style="display: none;"> We present an X-ray spectro-polarimetric analysis of the bright Seyfert galaxy NGC4151. The source has been observed with the Imaging X-ray Polarimetry Explorer (IXPE) for 700 ks, complemented with simultaneous XMM-Newton (50 ks) and NuSTAR (100 ks) pointings. A polarization degree $螤 = 4.9 {\pm} 1.1 \%$ and angle $唯= 86掳 {\pm} 7掳$ east of north ($68\%$ confidence level) are measured in the 2-8 keV energy range. The spectro-polarimetric analysis shows that the polarization could be entirely due to reflection. Given the low reflection flux in the IXPE band, this requires however a reflection with a very large ($> 38 \%$) polarization degree. Assuming more reasonable values, a polarization degree of the hot corona ranging from ${\sim}4$ to ${\sim}8\%$ is found. The observed polarization degree excludes a spherical lamppost geometry for the corona, suggesting instead a slab-like geometry, possibly a wedge, as determined via Monte Carlo simulations. This is further confirmed by the X-ray polarization angle, which coincides with the direction of the extended radio emission in this source, supposed to match the disc axis. NGC4151 is the first AGN with an X-ray polarization measure for the corona, illustrating the capabilities of X-ray polarimetry and IXPE in unveiling its geometry. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.12541v2-abstract-full').style.display = 'none'; document.getElementById('2303.12541v2-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 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 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">9 pages, 4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.02927">arXiv:2302.02927</a> <span> [<a href="https://arxiv.org/pdf/2302.02927">pdf</a>, <a href="https://arxiv.org/format/2302.02927">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/acba0f">10.3847/1538-3881/acba0f <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Handling Background in IXPE polarimetric data </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Soffitta%2C+P">Paolo Soffitta</a>, <a href="/search/astro-ph?searchtype=author&query=Costa%2C+E">Enrico Costa</a>, <a href="/search/astro-ph?searchtype=author&query=Ferrazzoli%2C+R">Riccardo Ferrazzoli</a>, <a href="/search/astro-ph?searchtype=author&query=La+Monaca%2C+F">Fabio La Monaca</a>, <a href="/search/astro-ph?searchtype=author&query=Rankin%2C+J">John Rankin</a>, <a href="/search/astro-ph?searchtype=author&query=Ratheesh%2C+A">Ajay Ratheesh</a>, <a href="/search/astro-ph?searchtype=author&query=Xie%2C+F">Fei Xie</a>, <a href="/search/astro-ph?searchtype=author&query=Baldini%2C+L">Luca Baldini</a>, <a href="/search/astro-ph?searchtype=author&query=Del+Monte%2C+E">Ettore Del Monte</a>, <a href="/search/astro-ph?searchtype=author&query=Ehlert%2C+S+R">Steven R. Ehlert</a>, <a href="/search/astro-ph?searchtype=author&query=Fabiani%2C+S">Sergio Fabiani</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=O%27Dell%2C+S+L">Stephen L. O'Dell</a>, <a href="/search/astro-ph?searchtype=author&query=Ramsey%2C+B+D">Brian D. Ramsey</a>, <a href="/search/astro-ph?searchtype=author&query=Rubini%2C+A">Alda Rubini</a>, <a href="/search/astro-ph?searchtype=author&query=Sgr%C3%B2%2C+C">Carmelo Sgr貌</a>, <a href="/search/astro-ph?searchtype=author&query=Silvestri%2C+S">Stefano Silvestri</a>, <a href="/search/astro-ph?searchtype=author&query=Tennant%2C+A+F">Allyn F. Tennant</a>, <a href="/search/astro-ph?searchtype=author&query=Weisskopf%2C+M+C">Martin C. Weisskopf</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="2302.02927v1-abstract-short" style="display: inline;"> IXPE (Imaging X-ray Polarimetry Explorer) is a Small Explorer mission by NASA and ASI, launched on December 9$^{th}$ 2021, dedicated to investigating X-ray polarimetry allowing angular-, time- and energy-resolved observations in the 2--8 keV energy band. IXPE is in Science Observation phase since January 2022; it comprises of three identical telescopes with grazing-incidence mirrors, each one havi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.02927v1-abstract-full').style.display = 'inline'; document.getElementById('2302.02927v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.02927v1-abstract-full" style="display: none;"> IXPE (Imaging X-ray Polarimetry Explorer) is a Small Explorer mission by NASA and ASI, launched on December 9$^{th}$ 2021, dedicated to investigating X-ray polarimetry allowing angular-, time- and energy-resolved observations in the 2--8 keV energy band. IXPE is in Science Observation phase since January 2022; it comprises of three identical telescopes with grazing-incidence mirrors, each one having in the focal plane a Gas Pixel Detector (GPD). In this paper, we present a possible guideline to obtain an optimal background selection in polarimetric analysis, and a rejection strategy to remove instrumental background. This work is based on the analysis of IXPE observations, aiming to improve as much as possible the polarimetric sensitivity. In particular, the developed strategies have been applied ``as a case study'' to the IXPE observation of the 4U 0142+61 magnetar. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.02927v1-abstract-full').style.display = 'none'; document.getElementById('2302.02927v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 February, 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">Journal ref:</span> AJ 165 143 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2211.13764">arXiv:2211.13764</a> <span> [<a href="https://arxiv.org/pdf/2211.13764">pdf</a>, <a href="https://arxiv.org/format/2211.13764">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/2041-8213/aca281">10.3847/2041-8213/aca281 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> X-ray Polarization Observations of BL Lacertae </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Perri%2C+M">Matteo Perri</a>, <a href="/search/astro-ph?searchtype=author&query=Puccetti%2C+S">Simonetta Puccetti</a>, <a href="/search/astro-ph?searchtype=author&query=Cavazzuti%2C+E">Elisabetta Cavazzuti</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Ehlert%2C+S+R">Steven R. Ehlert</a>, <a href="/search/astro-ph?searchtype=author&query=Madejski%2C+G">Grzegorz Madejski</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Ag%C3%ADs-Gonz%C3%A1lez%2C+B">Beatriz Ag铆s-Gonz谩lez</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">Giacomo Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardos%2C+M+I">Maria I. Bernardos</a>, <a href="/search/astro-ph?searchtype=author&query=Casanova%2C+V">V铆ctor Casanova</a>, <a href="/search/astro-ph?searchtype=author&query=Garc%C3%ADa-Comas%2C+M">Maya Garc铆a-Comas</a>, <a href="/search/astro-ph?searchtype=author&query=Husillos%2C+C">C茅sar Husillos</a>, <a href="/search/astro-ph?searchtype=author&query=Marchini%2C+A">Alessandro Marchini</a>, <a href="/search/astro-ph?searchtype=author&query=Sota%2C+A">Alfredo Sota</a>, <a href="/search/astro-ph?searchtype=author&query=Kouch%2C+P+M">Pouya M. Kouch</a>, <a href="/search/astro-ph?searchtype=author&query=Borman%2C+G+A">George A. Borman</a>, <a href="/search/astro-ph?searchtype=author&query=Kopatskaya%2C+E+N">Evgenia N. Kopatskaya</a> , et al. (121 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2211.13764v1-abstract-short" style="display: inline;"> Blazars are a class of jet-dominated active galactic nuclei with a typical double-humped spectral energy distribution. It is of common consensus the Synchrotron emission to be responsible for the low frequency peak, while the origin of the high frequency hump is still debated. The analysis of X-rays and their polarization can provide a valuable tool to understand the physical mechanisms responsibl… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.13764v1-abstract-full').style.display = 'inline'; document.getElementById('2211.13764v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2211.13764v1-abstract-full" style="display: none;"> Blazars are a class of jet-dominated active galactic nuclei with a typical double-humped spectral energy distribution. It is of common consensus the Synchrotron emission to be responsible for the low frequency peak, while the origin of the high frequency hump is still debated. The analysis of X-rays and their polarization can provide a valuable tool to understand the physical mechanisms responsible for the origin of high-energy emission of blazars. We report the first observations of BL Lacertae performed with the Imaging X-ray Polarimetry Explorer ({IXPE}), from which an upper limit to the polarization degree $螤_X<$12.6\% was found in the 2-8 keV band. We contemporaneously measured the polarization in radio, infrared, and optical wavelengths. Our multiwavelength polarization analysis disfavors a significant contribution of proton synchrotron radiation to the X-ray emission at these epochs. Instead, it supports a leptonic origin for the X-ray emission in BL Lac. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.13764v1-abstract-full').style.display = 'none'; document.getElementById('2211.13764v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">17 pages, 5 figures, accepted for publication in ApJL</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> 2023, ApJ Letters, 942, L10 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2211.01697">arXiv:2211.01697</a> <span> [<a href="https://arxiv.org/pdf/2211.01697">pdf</a>, <a href="https://arxiv.org/format/2211.01697">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/stac3189">10.1093/mnras/stac3189 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Mapping the circumnuclear regions of the Circinus galaxy with the Imaging X-ray Polarimetry Explorer </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ursini%2C+F">F. Ursini</a>, <a href="/search/astro-ph?searchtype=author&query=Marinucci%2C+A">A. Marinucci</a>, <a href="/search/astro-ph?searchtype=author&query=Matt%2C+G">G. Matt</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">S. Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Marin%2C+F">F. Marin</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">H. L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">R. Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">J. Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Rogantini%2C+D">D. Rogantini</a>, <a href="/search/astro-ph?searchtype=author&query=De+Rosa%2C+A">A. De Rosa</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">L. Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Garc%C3%ADa%2C+J+A">J. A. Garc铆a</a>, <a href="/search/astro-ph?searchtype=author&query=Ingram%2C+A">A. Ingram</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">D. E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Krawczynski%2C+H">H. Krawczynski</a>, <a href="/search/astro-ph?searchtype=author&query=Puccetti%2C+S">S. Puccetti</a>, <a href="/search/astro-ph?searchtype=author&query=Soffitta%2C+P">P. Soffitta</a>, <a href="/search/astro-ph?searchtype=author&query=Svoboda%2C+J">J. Svoboda</a>, <a href="/search/astro-ph?searchtype=author&query=Tombesi%2C+F">F. Tombesi</a>, <a href="/search/astro-ph?searchtype=author&query=Weisskopf%2C+M+C">M. C. Weisskopf</a>, <a href="/search/astro-ph?searchtype=author&query=Barnouin%2C+T">T. Barnouin</a>, <a href="/search/astro-ph?searchtype=author&query=Perri%2C+M">M. Perri</a>, <a href="/search/astro-ph?searchtype=author&query=Podgorny%2C+J">J. Podgorny</a>, <a href="/search/astro-ph?searchtype=author&query=Ratheesh%2C+A">A. Ratheesh</a>, <a href="/search/astro-ph?searchtype=author&query=Zaino%2C+A">A. Zaino</a> , et al. (72 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2211.01697v2-abstract-short" style="display: inline;"> We report on the Imaging X-ray Polarimetry Explorer (IXPE) observation of the closest and X-ray brightest Compton-thick active galactic nucleus (AGN), the Circinus galaxy. We find the source to be significantly polarized in the 2--6 keV band. From previous studies, the X-ray spectrum is known to be dominated by reflection components, both neutral (torus) and ionized (ionization cones). Our analysi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.01697v2-abstract-full').style.display = 'inline'; document.getElementById('2211.01697v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2211.01697v2-abstract-full" style="display: none;"> We report on the Imaging X-ray Polarimetry Explorer (IXPE) observation of the closest and X-ray brightest Compton-thick active galactic nucleus (AGN), the Circinus galaxy. We find the source to be significantly polarized in the 2--6 keV band. From previous studies, the X-ray spectrum is known to be dominated by reflection components, both neutral (torus) and ionized (ionization cones). Our analysis indicates that the polarization degree is $28 \pm 7$ per cent (at 68 per cent confidence level) for the neutral reflector, with a polarization angle of $18掳 \pm 5掳$, roughly perpendicular to the radio jet. The polarization of the ionized reflection is unconstrained. A comparison with Monte Carlo simulations of the polarization expected from the torus shows that the neutral reflector is consistent with being an equatorial torus with a half-opening angle of 45掳-55掳. This is the first X-ray polarization detection in a Seyfert galaxy, demonstrating the power of X-ray polarimetry in probing the geometry of the circumnuclear regions of AGNs, and confirming the basic predictions of standard Unification Models. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.01697v2-abstract-full').style.display = 'none'; document.getElementById('2211.01697v2-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 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, accepted for publication in MNRAS, authors list updated</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.06022">arXiv:2204.06022</a> <span> [<a href="https://arxiv.org/pdf/2204.06022">pdf</a>, <a href="https://arxiv.org/format/2204.06022">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4365/ac7eba">10.3847/1538-4365/ac7eba <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> ALMA/ACA CO Survey of the IC 1459 and NGC 4636 Groups: Environmental Effects on the Molecular Gas of Group Galaxies </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Lee%2C+B">Bumhyun Lee</a>, <a href="/search/astro-ph?searchtype=author&query=Wang%2C+J">Jing Wang</a>, <a href="/search/astro-ph?searchtype=author&query=Chung%2C+A">Aeree Chung</a>, <a href="/search/astro-ph?searchtype=author&query=Ho%2C+L+C">Luis C. Ho</a>, <a href="/search/astro-ph?searchtype=author&query=Wang%2C+R">Ran Wang</a>, <a href="/search/astro-ph?searchtype=author&query=Michiyama%2C+T">Tomonari Michiyama</a>, <a href="/search/astro-ph?searchtype=author&query=Molina%2C+J">Juan Molina</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+Y">Yongjung Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Shao%2C+L">Li Shao</a>, <a href="/search/astro-ph?searchtype=author&query=Kilborn%2C+V">Virginia Kilborn</a>, <a href="/search/astro-ph?searchtype=author&query=Wang%2C+S">Shun Wang</a>, <a href="/search/astro-ph?searchtype=author&query=Lin%2C+X">Xuchen Lin</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Catinella%2C+B">B. Catinella</a>, <a href="/search/astro-ph?searchtype=author&query=Cortese%2C+L">L. Cortese</a>, <a href="/search/astro-ph?searchtype=author&query=Deg%2C+N">N. Deg</a>, <a href="/search/astro-ph?searchtype=author&query=D%C3%A9nes%2C+H">H. D茅nes</a>, <a href="/search/astro-ph?searchtype=author&query=Elagali%2C+A">A. Elagali</a>, <a href="/search/astro-ph?searchtype=author&query=For%2C+B">Bi-Qing For</a>, <a href="/search/astro-ph?searchtype=author&query=Kleiner%2C+D">D. Kleiner</a>, <a href="/search/astro-ph?searchtype=author&query=Koribalski%2C+B+S">B. S. Koribalski</a>, <a href="/search/astro-ph?searchtype=author&query=Lee-Waddell%2C+K">K. Lee-Waddell</a>, <a href="/search/astro-ph?searchtype=author&query=Rhee%2C+J">J. Rhee</a>, <a href="/search/astro-ph?searchtype=author&query=Spekkens%2C+K">K. Spekkens</a>, <a href="/search/astro-ph?searchtype=author&query=Westmeier%2C+T">T. Westmeier</a> , et al. (8 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2204.06022v2-abstract-short" style="display: inline;"> We present new results of a 12CO(J=1-0) imaging survey using the Atacama Compact Array (ACA) for 31 HI detected galaxies in the IC 1459 and NGC 4636 groups. This is the first CO imaging survey for loose galaxy groups. We obtained well-resolved CO data (~0.7-1.5 kpc) for a total of 16 galaxies in two environments. By comparing our ACA CO data with the HI and UV data, we probe the impacts of the gro… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.06022v2-abstract-full').style.display = 'inline'; document.getElementById('2204.06022v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.06022v2-abstract-full" style="display: none;"> We present new results of a 12CO(J=1-0) imaging survey using the Atacama Compact Array (ACA) for 31 HI detected galaxies in the IC 1459 and NGC 4636 groups. This is the first CO imaging survey for loose galaxy groups. We obtained well-resolved CO data (~0.7-1.5 kpc) for a total of 16 galaxies in two environments. By comparing our ACA CO data with the HI and UV data, we probe the impacts of the group environment on the cold gas components (CO and HI gas) and star formation activity. We find that CO and/or HI morphologies are disturbed in our group members, some of which show highly asymmetric CO distributions (e.g., IC 5264, NGC 7421, and NGC 7418). In comparison with isolated galaxies in the xCOLD GASS sample, our group galaxies tend to have low star formation rates and low H2 gas fractions. Our findings suggest that the group environment can change the distribution of cold gas components, including the molecular gas, and star formation properties of galaxies. This is supporting evidence that preprocessing in the group-like environment can play an important role in galaxy evolution. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.06022v2-abstract-full').style.display = 'none'; document.getElementById('2204.06022v2-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 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 12 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">42 pages, 29 figures, 6 tables, published in ApJS</span> </p> </li> </ol> <div class="is-hidden-tablet">  <span class="help" style="display: inline-block;"><a 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