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aria-current="page">4 </a> </li> </ul> </nav> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/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/2411.00350">arXiv:2411.00350</a> <span> [<a href="https://arxiv.org/pdf/2411.00350">pdf</a>, <a href="https://arxiv.org/format/2411.00350">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"> X-ray and Radio Campaign of the Z-source GX 340+0 II: the X-ray polarization in the normal branch </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Bhargava%2C+Y">Yash Bhargava</a>, <a href="/search/astro-ph?searchtype=author&query=Russell%2C+T+D">Thomas D. Russell</a>, <a href="/search/astro-ph?searchtype=author&query=Ng%2C+M">Mason Ng</a>, <a href="/search/astro-ph?searchtype=author&query=Balasubramanian%2C+A">Arvind Balasubramanian</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+L">Liang Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Ravi%2C+S">Swati Ravi</a>, <a href="/search/astro-ph?searchtype=author&query=Jadoliya%2C+V">Vishal Jadoliya</a>, <a href="/search/astro-ph?searchtype=author&query=Bhattacharyya%2C+S">Sudip Bhattacharyya</a>, <a href="/search/astro-ph?searchtype=author&query=Pahari%2C+M">Mayukh Pahari</a>, <a href="/search/astro-ph?searchtype=author&query=Homan%2C+J">Jeroen Homan</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=Chakrabarty%2C+D">Deepto Chakrabarty</a>, <a href="/search/astro-ph?searchtype=author&query=Carotenuto%2C+F">Francesco Carotenuto</a>, <a href="/search/astro-ph?searchtype=author&query=Kaushik%2C+A">Aman Kaushik</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2411.00350v1-abstract-short" style="display: inline;"> We present the first X-ray polarization measurement of the neutron star low-mass X-ray binary and Z-source, GX 340$+$0, in the normal branch (NB) using a 200 ks observation with the Imaging X-ray Polarimetric Explorer (IXPE). This observation was performed in 2024 August. Along with IXPE, we also conducted simultaneous observations with NICER, AstroSat, Insight-HXMT, ATCA, and GMRT to investigate… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.00350v1-abstract-full').style.display = 'inline'; document.getElementById('2411.00350v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.00350v1-abstract-full" style="display: none;"> We present the first X-ray polarization measurement of the neutron star low-mass X-ray binary and Z-source, GX 340$+$0, in the normal branch (NB) using a 200 ks observation with the Imaging X-ray Polarimetric Explorer (IXPE). This observation was performed in 2024 August. Along with IXPE, we also conducted simultaneous observations with NICER, AstroSat, Insight-HXMT, ATCA, and GMRT to investigate the broadband spectral and timing properties in the X-ray and radio wavelengths. During the campaign, the source traced a complete Z-track during the IXPE observation but spent most of the time in the NB. We measure X-ray polarization degree (PD) of $1.22\pm0.25\%$ in the 2-8 keV energy band with a polarization angle (PA) of $38\pm6^\circ$. The PD in the NB is observed to be weaker than in the horizontal branch (HB) but aligned in the same direction. The PD of the source exhibits a marginal increase with energy while the PA shows no energy dependence. The joint spectro-polarimetric modeling is consistent with the observed X-ray polarization originating from a single spectral component from the blackbody, the Comptonized emission, or reflection feature, while the disk emission does not contribute towards the X-ray polarization. GMRT observations at 1.26 GHz during HB had a tentative detection at 4.5$\pm$0.7 mJy while ATCA observations a day later during the NB detected the source at 0.70$\pm$0.05 mJy and 0.59$\pm$0.05 mJy in the 5.5 & 9 GHz bands, respectively, suggesting an evolving jet structure depending on the Z-track position. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.00350v1-abstract-full').style.display = 'none'; document.getElementById('2411.00350v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 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">17 pages, 5 figures, 4 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/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/2408.11168">arXiv:2408.11168</a> <span> [<a href="https://arxiv.org/pdf/2408.11168">pdf</a>, <a href="https://arxiv.org/format/2408.11168">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"> Characterization of X-ray Detectors in the MIT X-ray Polarimetry Beamline </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Heine%2C+S+N+T">Sarah N. T. Heine</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=Schneider%2C+B">Benjamin Schneider</a>, <a href="/search/astro-ph?searchtype=author&query=Lamar%2C+B">Beverly Lamar</a>, <a href="/search/astro-ph?searchtype=author&query=Kothnur%2C+N">Nithya Kothnur</a>, <a href="/search/astro-ph?searchtype=author&query=Garner%2C+A">Alan Garner</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="2408.11168v1-abstract-short" style="display: inline;"> The MIT X-ray Polarimetry Beamline is a facility that we developed for testing components for possible use in X-ray polarimetry. Over the past few years, we have demonstrated that the X-ray source can generate nearly 100% polarized X-rays at various energies from 183 eV (Boron K$伪$) to 705 eV (Fe L$伪$) using a laterally graded multilayer coated mirror (LGML) oriented at 45掳 to the source. The posi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.11168v1-abstract-full').style.display = 'inline'; document.getElementById('2408.11168v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2408.11168v1-abstract-full" style="display: none;"> The MIT X-ray Polarimetry Beamline is a facility that we developed for testing components for possible use in X-ray polarimetry. Over the past few years, we have demonstrated that the X-ray source can generate nearly 100% polarized X-rays at various energies from 183 eV (Boron K$伪$) to 705 eV (Fe L$伪$) using a laterally graded multilayer coated mirror (LGML) oriented at 45掳 to the source. The position angle of the polarization can be rotated through a range of roughly 150掳. In a downstream chamber, we can orient a Princeton Instruments MTE1300B CCD camera to observe the polarized light either directly or after reflection at 45掳 by a second LGML. In support of the REDSoX Polarimeter project, we have tested four other detectors by directly comparing them to the PI camera. Two were CCD cameras: a Raptor Eagle XV and a CCID94 produced by MIT Lincoln Laboratories, and two had sCMOS sensors: the Sydor Wraith with a GSENSE 400BSI sensor and a custom Sony IMX290 sensor. We will show results comparing quantum efficiencies and event images in the soft X-ray band. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2408.11168v1-abstract-full').style.display = 'none'; document.getElementById('2408.11168v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.17243">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/2407.12779">arXiv:2407.12779</a> <span> [<a href="https://arxiv.org/pdf/2407.12779">pdf</a>, <a href="https://arxiv.org/format/2407.12779">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"> Analysis of Crab X-ray Polarization using Deeper IXPE Observations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Wong%2C+J">Josephine Wong</a>, <a href="/search/astro-ph?searchtype=author&query=Mizuno%2C+T">Tsunefumi Mizuno</a>, <a href="/search/astro-ph?searchtype=author&query=Bucciantini%2C+N">Niccol贸 Bucciantini</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=Yang%2C+Y">Yi-Jung Yang</a>, <a href="/search/astro-ph?searchtype=author&query=Liu%2C+K">Kuan Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Deng%2C+W">Wei Deng</a>, <a href="/search/astro-ph?searchtype=author&query=Goya%2C+K">Kazuho Goya</a>, <a href="/search/astro-ph?searchtype=author&query=Xie%2C+F">Fei Xie</a>, <a href="/search/astro-ph?searchtype=author&query=Pilia%2C+M">Maura Pilia</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">Philip Kaaret</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=Silvestri%2C+S">Stefano Silvestri</a>, <a href="/search/astro-ph?searchtype=author&query=Ng%2C+C+-">C. -Y. Ng</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+C">Chien-Ting Chen</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>, <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>, <a href="/search/astro-ph?searchtype=author&query=Brez%2C+A">Alessandro Brez</a> , et al. (76 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="2407.12779v1-abstract-short" style="display: inline;"> We present Crab X-ray polarization measurements using IXPE data with a total exposure of 300ks, three times more than the initial 2022 discovery paper. Polarization is detected in three times more pulsar phase bins, revealing an S-shaped $+40^\circ$ polarization angle sweep in the main pulse and ${>}1蟽$ departures from the OPTIMA optical polarization in both pulses, suggesting different radiation… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.12779v1-abstract-full').style.display = 'inline'; document.getElementById('2407.12779v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.12779v1-abstract-full" style="display: none;"> We present Crab X-ray polarization measurements using IXPE data with a total exposure of 300ks, three times more than the initial 2022 discovery paper. Polarization is detected in three times more pulsar phase bins, revealing an S-shaped $+40^\circ$ polarization angle sweep in the main pulse and ${>}1蟽$ departures from the OPTIMA optical polarization in both pulses, suggesting different radiation mechanisms or sites for the polarized emission at the two wavebands. Our polarization map of the inner nebula reveals a toroidal magnetic field, as seen in prior IXPE analyses. Along the southern jet, the magnetic field orientation relative to the jet axis changes from perpendicular to parallel and the polarization degree decreases by ${\sim}6\%$. These observations may be explained by kink instabilities along the jet or a collision with a dense, jet-deflecting medium at the tip. Using spectropolarimetric analysis, we find asymmetric polarization in the four quadrants of the inner nebula, as expected for a toroidal field geometry, and a spatial correlation between polarization degree and photon index. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.12779v1-abstract-full').style.display = 'none'; document.getElementById('2407.12779v1-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 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">14 pages, 7 figures, 3 tables. Accepted by 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/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/2407.09432">arXiv:2407.09432</a> <span> [<a href="https://arxiv.org/pdf/2407.09432">pdf</a>, <a href="https://arxiv.org/format/2407.09432">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"> International Astrophysical Consortium for High-energy Calibration: Summary of the 15th IACHEC Workshop </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Madsen%2C+K+K">K. K. Madsen</a>, <a href="/search/astro-ph?searchtype=author&query=Burwitz%2C+V">V. Burwitz</a>, <a href="/search/astro-ph?searchtype=author&query=Forster%2C+K">K. Forster</a>, <a href="/search/astro-ph?searchtype=author&query=Grant%2C+C+E">C. E. Grant</a>, <a href="/search/astro-ph?searchtype=author&query=Guainazzi%2C+M">M. Guainazzi</a>, <a href="/search/astro-ph?searchtype=author&query=Kashyap%2C+V">V. Kashyap</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=Miller%2C+E+D">E. D. Miller</a>, <a href="/search/astro-ph?searchtype=author&query=Natalucci%2C+L">L. Natalucci</a>, <a href="/search/astro-ph?searchtype=author&query=Plucinsky%2C+P+P">P. P. Plucinsky</a>, <a href="/search/astro-ph?searchtype=author&query=Terada%2C+Y">Y. Terada</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="2407.09432v1-abstract-short" style="display: inline;"> In this report, we summarize the activities of the International Astronomical Consortium for High Energy Calibration (IACHEC) from the 15th IACHEC Workshop in Pelham, Germany. Sixty scientists directly involved in the calibration of operational and future high-energy missions gathered for 3.5 days to discuss the status of the cross-calibration between the current international complement of X-ray… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.09432v1-abstract-full').style.display = 'inline'; document.getElementById('2407.09432v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.09432v1-abstract-full" style="display: none;"> In this report, we summarize the activities of the International Astronomical Consortium for High Energy Calibration (IACHEC) from the 15th IACHEC Workshop in Pelham, Germany. Sixty scientists directly involved in the calibration of operational and future high-energy missions gathered for 3.5 days to discuss the status of the cross-calibration between the current international complement of X-ray observatories and the possibilities to improve it. This summary consists of reports from the Working Groups with topics ranging across the identification and characterization of standard calibration sources, multi-observatory cross-calibration campaigns, appropriate and new statistical techniques, calibration of instruments and characterization of background, preservation of knowledge, and results for the benefit of the astronomical community. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.09432v1-abstract-full').style.display = 'none'; document.getElementById('2407.09432v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 July, 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">10 pages, 1 figure. arXiv admin note: text overlap with arXiv:2111.01613</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.12014">arXiv:2406.12014</a> <span> [<a href="https://arxiv.org/pdf/2406.12014">pdf</a>, <a href="https://arxiv.org/format/2406.12014">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"> An IXPE-Led X-ray Spectro-Polarimetric Campaign on the Soft State of Cygnus X-1: X-ray Polarimetric Evidence for Strong Gravitational Lensing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Steiner%2C+J+F">James F. Steiner</a>, <a href="/search/astro-ph?searchtype=author&query=Nathan%2C+E">Edward Nathan</a>, <a href="/search/astro-ph?searchtype=author&query=Hu%2C+K">Kun Hu</a>, <a href="/search/astro-ph?searchtype=author&query=Krawczynski%2C+H">Henric Krawczynski</a>, <a href="/search/astro-ph?searchtype=author&query=Dovciak%2C+M">Michal Dovciak</a>, <a href="/search/astro-ph?searchtype=author&query=Veledina%2C+A">Alexandra Veledina</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Svoboda%2C+J">Jiri Svoboda</a>, <a href="/search/astro-ph?searchtype=author&query=Alabarta%2C+K">Kevin Alabarta</a>, <a href="/search/astro-ph?searchtype=author&query=Parra%2C+M">Maxime Parra</a>, <a href="/search/astro-ph?searchtype=author&query=Bhargava%2C+Y">Yash Bhargava</a>, <a href="/search/astro-ph?searchtype=author&query=Matt%2C+G">Giorgio Matt</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Petrucci%2C+P">Pierre-Olivier Petrucci</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=Baglio%2C+M+C">M. Cristina Baglio</a>, <a href="/search/astro-ph?searchtype=author&query=Baldini%2C+L">Luca Baldini</a>, <a href="/search/astro-ph?searchtype=author&query=Barnier%2C+S">Samuel Barnier</a>, <a href="/search/astro-ph?searchtype=author&query=Bhattacharyya%2C+S">Sudip Bhattacharyya</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">Stefano Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Brigitte%2C+M">Maimouna Brigitte</a>, <a href="/search/astro-ph?searchtype=author&query=Cabezas%2C+M">Mauricio Cabezas</a>, <a href="/search/astro-ph?searchtype=author&query=Cangemi%2C+F">Floriane Cangemi</a>, <a href="/search/astro-ph?searchtype=author&query=Capitanio%2C+F">Fiamma Capitanio</a>, <a href="/search/astro-ph?searchtype=author&query=Casey%2C+J">Jacob Casey</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="2406.12014v1-abstract-short" style="display: inline;"> We present the first X-ray spectropolarimetric results for Cygnus X-1 in its soft state from a campaign of five IXPE observations conducted during 2023 May-June. Companion multiwavelength data during the campaign are likewise shown. The 2-8 keV X-rays exhibit a net polarization degree PD=1.99%+/-0.13% (68% confidence). The polarization signal is found to increase with energy across IXPE's 2-8 keV… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.12014v1-abstract-full').style.display = 'inline'; document.getElementById('2406.12014v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.12014v1-abstract-full" style="display: none;"> We present the first X-ray spectropolarimetric results for Cygnus X-1 in its soft state from a campaign of five IXPE observations conducted during 2023 May-June. Companion multiwavelength data during the campaign are likewise shown. The 2-8 keV X-rays exhibit a net polarization degree PD=1.99%+/-0.13% (68% confidence). The polarization signal is found to increase with energy across IXPE's 2-8 keV bandpass. The polarized X-rays exhibit an energy-independent polarization angle of PA=-25.7+/-1.8 deg. East of North (68% confidence). This is consistent with being aligned to Cyg X-1's AU-scale compact radio jet and its pc-scale radio lobes. In comparison to earlier hard-state observations, the soft state exhibits a factor of 2 lower polarization degree, but a similar trend with energy and a similar (also energy-independent) position angle. When scaling by the natural unit of the disk temperature, we find the appearance of a consistent trendline in the polarization degree between soft and hard states. Our favored polarimetric model indicates Cyg X-1's spin is likely high (a* above ~0.96). The substantial X-ray polarization in Cyg X-1's soft state is most readily explained as resulting from a large portion of X-rays emitted from the disk returning and reflecting off the disk surface, generating a high polarization degree and a polarization direction parallel to the black hole spin axis and radio jet. In IXPE's bandpass, the polarization signal is dominated by the returning reflection emission. This constitutes polarimetric evidence for strong gravitational lensing of X-rays close to the black hole. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.12014v1-abstract-full').style.display = 'none'; document.getElementById('2406.12014v1-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 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">20 pages, accepted for publication in ApJL</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.08988">arXiv:2406.08988</a> <span> [<a href="https://arxiv.org/pdf/2406.08988">pdf</a>, <a href="https://arxiv.org/format/2406.08988">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/10.1051/0004-6361/202450937">10.1051/0004-6361/202450937 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Probing the polarized emission from SMC X-1: the brightest X-ray pulsar observed by IXPE </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Forsblom%2C+S+V">Sofia V. Forsblom</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=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">Victor Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Mushtukov%2C+A+A">Alexander A. Mushtukov</a>, <a href="/search/astro-ph?searchtype=author&query=Ng%2C+M">Mason Ng</a>, <a href="/search/astro-ph?searchtype=author&query=Ravi%2C+S">Swati Ravi</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=Di+Marco%2C+A">Alessandro Di Marco</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=Malacaria%2C+C">Christian Malacaria</a>, <a href="/search/astro-ph?searchtype=author&query=Mastroserio%2C+G">Guglielmo Mastroserio</a>, <a href="/search/astro-ph?searchtype=author&query=Loktev%2C+V">Vladislav Loktev</a>, <a href="/search/astro-ph?searchtype=author&query=Possenti%2C+A">Andrea Possenti</a>, <a href="/search/astro-ph?searchtype=author&query=Suleimanov%2C+V+F">Valery F. Suleimanov</a>, <a href="/search/astro-ph?searchtype=author&query=Taverna%2C+R">Roberto Taverna</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Ivan Agudo</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. (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="2406.08988v1-abstract-short" style="display: inline;"> Recent observations of X-ray pulsars (XRPs) performed by the Imaging X-ray Polarimetry Explorer (IXPE) have made it possible to investigate the intricate details of these objects in a new way, thanks to the added value of X-ray polarimetry. Here we present the results of the IXPE observations of SMC X-1, a member of the small group of XRPs displaying super-orbital variability. SMC X-1 was observed… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.08988v1-abstract-full').style.display = 'inline'; document.getElementById('2406.08988v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.08988v1-abstract-full" style="display: none;"> Recent observations of X-ray pulsars (XRPs) performed by the Imaging X-ray Polarimetry Explorer (IXPE) have made it possible to investigate the intricate details of these objects in a new way, thanks to the added value of X-ray polarimetry. Here we present the results of the IXPE observations of SMC X-1, a member of the small group of XRPs displaying super-orbital variability. SMC X-1 was observed by IXPE three separate times during the high state of its super-orbital period. The observed luminosity in the 2-8 keV energy band of $L=2\times10^{38}$ erg/s makes SMC X-1 the brightest XRP ever observed by IXPE. We detect significant polarization in all three observations, with values of the phase-averaged polarization degree (PD) and polarization angle (PA) of $3.2\pm0.8$% and $97掳\pm8掳$ for Observation 1, $3.0\pm0.9$% and $90掳\pm8掳$ for Observation 2, and $5.5\pm1.1$% and $80掳\pm6掳$ for Observation 3, for the spectro-polarimetric analysis. The observed PD shows an increase over time with decreasing luminosity, while the PA decreases in decrements of 10掳. The phase-resolved spectro-polarimetric analysis reveals significant detection of polarization in three out of seven phase bins, with the PD ranging between 2% and 10%, and a corresponding range in the PA from $\sim$70掳 to $\sim$100掳. The pulse-phase resolved PD displays an apparent anti-correlation with the flux. Using the rotating vector model, we obtain constraints on the pulsar's geometrical properties for the individual observations. The position angle of the pulsar displays an evolution over time supporting the idea that we observe changes related to different super-orbital phases. Scattering in the wind of the precessing accretion disk may be responsible for the behavior of the polarimetric properties observed during the high-state of SMC X-1's super-orbital period. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.08988v1-abstract-full').style.display = 'none'; document.getElementById('2406.08988v1-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 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">11 pages, 11 figures, submitted to A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 691, A216 (2024) </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/2405.19324">arXiv:2405.19324</a> <span> [<a href="https://arxiv.org/pdf/2405.19324">pdf</a>, <a href="https://arxiv.org/format/2405.19324">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"> X-ray and Radio campaign of the Z-source GX 340+0: discovery of X-ray polarization and its implications </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Bhargava%2C+Y">Yash Bhargava</a>, <a href="/search/astro-ph?searchtype=author&query=Ng%2C+M">Mason Ng</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+L">Liang Zhang</a>, <a href="/search/astro-ph?searchtype=author&query=Balasubramanian%2C+A">Arvind Balasubramanian</a>, <a href="/search/astro-ph?searchtype=author&query=Russell%2C+T+D">Thomas D. Russell</a>, <a href="/search/astro-ph?searchtype=author&query=Kaushik%2C+A">Aman Kaushik</a>, <a href="/search/astro-ph?searchtype=author&query=Jadoliya%2C+V">Vishal Jadoliya</a>, <a href="/search/astro-ph?searchtype=author&query=Ravi%2C+S">Swati Ravi</a>, <a href="/search/astro-ph?searchtype=author&query=Bhattacharyya%2C+S">Sudip Bhattacharyya</a>, <a href="/search/astro-ph?searchtype=author&query=Pahari%2C+M">Mayukh Pahari</a>, <a href="/search/astro-ph?searchtype=author&query=Homan%2C+J">Jeroen Homan</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=Chakrabarty%2C+D">Deepto Chakrabarty</a>, <a href="/search/astro-ph?searchtype=author&query=Carotenuto%2C+F">Francesco Carotenuto</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2405.19324v1-abstract-short" style="display: inline;"> We present the discovery of X-ray polarization from the neutron star low-mass X-ray binary and Z-source, GX~340$+$0, using an Imaging X-ray Polarimetry Explorer (IXPE) observation in March 2024. Along with the IXPE observation, we conducted an extensive X-ray and radio monitoring campaign to ascertain the source properties during and around the IXPE observation. The source was within the horizonta… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.19324v1-abstract-full').style.display = 'inline'; document.getElementById('2405.19324v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.19324v1-abstract-full" style="display: none;"> We present the discovery of X-ray polarization from the neutron star low-mass X-ray binary and Z-source, GX~340$+$0, using an Imaging X-ray Polarimetry Explorer (IXPE) observation in March 2024. Along with the IXPE observation, we conducted an extensive X-ray and radio monitoring campaign to ascertain the source properties during and around the IXPE observation. The source was within the horizontal branch throughout the multiwavelength campaign. We measured a significant X-ray polarization in 2--8 keV with polarization degree (PD) = $4.02 \pm 0.35$% and polarization angle (PA) = $37.6 \pm 2.5^\circ$. The energy-dependent polarization indicates that in the 2-2.5 keV energy range, the PA is much lower, $\sim9\pm8^\circ$, while other energy bands are consistent with the PA found over 2.5--8 keV. The simultaneous AstroSat-IXPE spectro-polarimetric observations provide some evidence for independent polarization from various spectral components, hinting at a disparity in the PA from the accretion disk and the Comptonized emission, while suggesting an unpolarized emission from the blackbody component. Radio observations in the 0.7--9 GHz frequency range reveal a non-detection of radio emission in 0.7-1.5 GHz and a significant detection in 5.5--9 GHz, suggesting the presence of a spectral break in 1.5-5.5 GHz. Using ATCA observation we place upper limits on the radio polarization at $<$6% on the linear polarization and $<$4% on the circular polarization at 3$蟽$ level. We discuss the origin of the X-ray polarization and its implications on the geometry of the spectral components. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.19324v1-abstract-full').style.display = 'none'; document.getElementById('2405.19324v1-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 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">Submitted in ApJL, 4 figures, 3 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/2405.08107">arXiv:2405.08107</a> <span> [<a href="https://arxiv.org/pdf/2405.08107">pdf</a>, <a href="https://arxiv.org/format/2405.08107">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="Solar and Stellar Astrophysics">astro-ph.SR</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/10.1051/0004-6361/202450696">10.1051/0004-6361/202450696 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Studying geometry of the ultraluminous X-ray pulsar Swift J0243.6+6124 using X-ray and optical polarimetry </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</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=Doroshenko%2C+V">Victor Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Forsblom%2C+S+V">Sofia V. Forsblom</a>, <a href="/search/astro-ph?searchtype=author&query=Jenke%2C+P">Peter Jenke</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">Philip Kaaret</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=Blinov%2C+D">Dmitry Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Kravtsov%2C+V">Vadim Kravtsov</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Tzouvanou%2C+A">Anastasia Tzouvanou</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=Heyl%2C+J">Jeremy Heyl</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=Mushtukov%2C+A+A">Alexander A. Mushtukov</a>, <a href="/search/astro-ph?searchtype=author&query=Pavlov%2C+G+G">George G. Pavlov</a>, <a href="/search/astro-ph?searchtype=author&query=Salganik%2C+A">Alexander Salganik</a>, <a href="/search/astro-ph?searchtype=author&query=Veledina%2C+A">Alexandra Veledina</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=Zane%2C+S">Silvia Zane</a>, <a href="/search/astro-ph?searchtype=author&query=Loktev%2C+V">Vladislav Loktev</a>, <a href="/search/astro-ph?searchtype=author&query=Suleimanov%2C+V+F">Valery F. Suleimanov</a>, <a href="/search/astro-ph?searchtype=author&query=Wilson-Hodge%2C+C">Colleen Wilson-Hodge</a>, <a href="/search/astro-ph?searchtype=author&query=Berdyugina%2C+S+V">Svetlana V. Berdyugina</a>, <a href="/search/astro-ph?searchtype=author&query=Kagitani%2C+M">Masato Kagitani</a> , et al. (86 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="2405.08107v2-abstract-short" style="display: inline;"> Discovery of pulsations from a number of ULXs proved that accretion onto neutron stars can produce luminosities exceeding the Eddington limit by several orders of magnitude. The conditions necessary to achieve such high luminosities as well as the exact geometry of the accretion flow in the neutron star vicinity are, however, a matter of debate. The pulse phase-resolved polarization measurements t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.08107v2-abstract-full').style.display = 'inline'; document.getElementById('2405.08107v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2405.08107v2-abstract-full" style="display: none;"> Discovery of pulsations from a number of ULXs proved that accretion onto neutron stars can produce luminosities exceeding the Eddington limit by several orders of magnitude. The conditions necessary to achieve such high luminosities as well as the exact geometry of the accretion flow in the neutron star vicinity are, however, a matter of debate. The pulse phase-resolved polarization measurements that became possible with the launch of the Imaging X-ray Polarimetry Explorer (IXPE) can be used to determine the pulsar geometry and its orientation relative to the orbital plane. They provide an avenue to test different theoretical models of ULX pulsars. In this paper we present the results of three IXPE observations of the first Galactic ULX pulsar Swift J0243.6+6124 during its 2023 outburst. We find strong variations in the polarization characteristics with the pulsar phase. The average polarization degree increases from about 5% to 15% as the flux dropped by a factor of three in the course of the outburst. The polarization angle (PA) as a function of the pulsar phase shows two peaks in the first two observations, but changes to a characteristic sawtooth pattern in the remaining data set. This is not consistent with a simple rotating vector model. Assuming the existence of an additional constant polarized component, we were able to fit the three observations with a common rotating vector model and obtain constraints on the pulsar geometry. In particular, we find the pulsar angular momentum inclination with respect to the line of sight of 15-40 deg, the magnetic obliquity of 60-80 deg, and the pulsar spin position angle of -50 deg, which significantly differs from the constant component PA of about 10 deg. Combining these X-ray measurements with the optical PA, we find evidence for at least a 30 deg misalignment between the pulsar angular momentum and the binary orbital axis. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2405.08107v2-abstract-full').style.display = 'none'; document.getElementById('2405.08107v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 November, 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">13 pages, 10 figures, version published in A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 691, A123 (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/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/2402.02504">arXiv:2402.02504</a> <span> [<a href="https://arxiv.org/pdf/2402.02504">pdf</a>, <a href="https://arxiv.org/format/2402.02504">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 detection of polarization in X-rays for PSR B0540-69 and its nebula </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Xie%2C+F">Fei Xie</a>, <a href="/search/astro-ph?searchtype=author&query=Wong%2C+J">Josephine Wong</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=Romani%2C+R+W">Roger W. Romani</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=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Bucciantini%2C+N">Niccol貌 Bucciantini</a>, <a href="/search/astro-ph?searchtype=author&query=Liu%2C+K">Kuan Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Ng%2C+C">Chi-Yung Ng</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Lalla%2C+N">Niccol貌 Di Lalla</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=Costa%2C+E">Enrico Costa</a>, <a href="/search/astro-ph?searchtype=author&query=Soffitta%2C+P">Paolo Soffitta</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Bachetti%2C+M">Matteo Bachetti</a>, <a href="/search/astro-ph?searchtype=author&query=Pilia%2C+M">Maura Pilia</a>, <a href="/search/astro-ph?searchtype=author&query=Rankin%2C+J">John Rankin</a>, <a href="/search/astro-ph?searchtype=author&query=Fabiani%2C+S">Sergio Fabiani</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>, <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> , 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="2402.02504v1-abstract-short" style="display: inline;"> We report on X-ray polarization measurements of the extra-galactic Crab-like PSR B0540-69 and its Pulsar Wind Nebula (PWN) in the Large Magellanic Cloud (LMC), using a ~850 ks Imaging X-ray Polarimetry Explorer (IXPE) exposure. The PWN is unresolved by IXPE. No statistically significant polarization is detected for the image-averaged data, giving a 99% confidence polarization upper limit (MDP99) o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.02504v1-abstract-full').style.display = 'inline'; document.getElementById('2402.02504v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.02504v1-abstract-full" style="display: none;"> We report on X-ray polarization measurements of the extra-galactic Crab-like PSR B0540-69 and its Pulsar Wind Nebula (PWN) in the Large Magellanic Cloud (LMC), using a ~850 ks Imaging X-ray Polarimetry Explorer (IXPE) exposure. The PWN is unresolved by IXPE. No statistically significant polarization is detected for the image-averaged data, giving a 99% confidence polarization upper limit (MDP99) of 5.3% in 2-8 keV energy range. However, a phase-resolved analysis detects polarization for both the nebula and pulsar in the 4-6 keV energy range. For the PWN defined as the off-pulse phases, the polarization degree (PD) of (24.5 ${\pm}$ 5.3)% and polarization angle (PA) of (78.1 ${\pm}$ 6.2)掳 is detected at 4.6$蟽$ significance level, consistent with the PA observed in the optical band. In a single on-pulse window, a hint of polarization is measured at 3.8$蟽$ with polarization degree of (50.0 ${\pm}$ 13.1)% and polarization angle of (6.2 ${\pm}$ 7.4)掳. A 'simultaneous' PSR/PWN analysis finds two bins at the edges of the pulse exceeding 3$蟽$ PD significance, with PD of (68 ${\pm}$ 20)% and (62 ${\pm}$ 20)%; intervening bins at 2-3$蟽$ significance have lower PD, hinting at additional polarization structure. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.02504v1-abstract-full').style.display = 'none'; document.getElementById('2402.02504v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 7 figures, 4 tables, author's version of the paper 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/2401.13058">arXiv:2401.13058</a> <span> [<a href="https://arxiv.org/pdf/2401.13058">pdf</a>, <a href="https://arxiv.org/format/2401.13058">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/10.1051/0004-6361/202449318">10.1051/0004-6361/202449318 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Discovery of a strong rotation of the X-ray polarization angle in the galactic burster GX 13+1 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Bobrikova%2C+A">Anna Bobrikova</a>, <a href="/search/astro-ph?searchtype=author&query=Forsblom%2C+S+V">Sofia V. Forsblom</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=La+Monaca%2C+F">Fabio La Monaca</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Ng%2C+M">Mason Ng</a>, <a href="/search/astro-ph?searchtype=author&query=Ravi%2C+S">Swati Ravi</a>, <a href="/search/astro-ph?searchtype=author&query=Loktev%2C+V">Vladislav Loktev</a>, <a href="/search/astro-ph?searchtype=author&query=Kajava%2C+J+J+E">Jari J. E. Kajava</a>, <a href="/search/astro-ph?searchtype=author&query=Ursini%2C+F">Francesco Ursini</a>, <a href="/search/astro-ph?searchtype=author&query=Veledina%2C+A">Alexandra Veledina</a>, <a href="/search/astro-ph?searchtype=author&query=Rogantini%2C+D">Daniele Rogantini</a>, <a href="/search/astro-ph?searchtype=author&query=Salmi%2C+T">Tuomo Salmi</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">Stefano Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Capitanio%2C+F">Fiamma Capitanio</a>, <a href="/search/astro-ph?searchtype=author&query=Done%2C+C">Chris Done</a>, <a href="/search/astro-ph?searchtype=author&query=Fabiani%2C+S">Sergio Fabiani</a>, <a href="/search/astro-ph?searchtype=author&query=Gnarini%2C+A">Andrea Gnarini</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=Matt%2C+G">Giorgio Matt</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Nitindala%2C+A+P">Anagha P. Nitindala</a>, <a href="/search/astro-ph?searchtype=author&query=Rankin%2C+J">John Rankin</a>, <a href="/search/astro-ph?searchtype=author&query=Weisskopf%2C+M+C">Martin C. Weisskopf</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="2401.13058v2-abstract-short" style="display: inline;"> Weakly magnetized neutron stars in X-ray binaries show complex phenomenology with several spectral components that can be associated with the accretion disk, boundary and/or spreading layer, a corona, and a wind. Spectroscopic information alone is, however, not enough to disentangle these components. Additional information about the nature of the spectral components and in particular the geometry… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.13058v2-abstract-full').style.display = 'inline'; document.getElementById('2401.13058v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.13058v2-abstract-full" style="display: none;"> Weakly magnetized neutron stars in X-ray binaries show complex phenomenology with several spectral components that can be associated with the accretion disk, boundary and/or spreading layer, a corona, and a wind. Spectroscopic information alone is, however, not enough to disentangle these components. Additional information about the nature of the spectral components and in particular the geometry of the emission region can be provided by X-ray polarimetry. One of the objects of the class, a bright, persistent, and rather peculiar galactic Type I X-ray burster was observed with the Imaging X-ray Polarimetry Explorer (IXPE) and the X-ray Multi-Mirror Mission Newton (XMM-Newton). Using the XMM-Newton data we estimated the current state of the source as well as detected strong absorption lines associated with the accretion disk wind. IXPE data showed the source to be significantly polarized in the 2-8 keV energy band with the overall polarization degree (PD) of 1.4% at a polarization angle (PA) of -2 degrees (errors at 68% confidence level). During the two-day long observation, we detected rotation of the PA by about 70 degrees with the corresponding changes in the PD from 2% to non-detectable and then up to 5%. These variations in polarization properties are not accompanied by visible changes in spectroscopic characteristics. The energy-resolved polarimetric analysis showed a significant change in polarization, from being strongly dependent on energy at the beginning of the observation to being almost constant with energy in the later parts of the observation. As a possible interpretation, we suggest the presence of a constant component of polarization, strong wind scattering, or different polarization of the two main spectral components with individually peculiar behavior. The rotation of the PA suggests a 30-degree misalignment of the neutron star spin from the orbital axis. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.13058v2-abstract-full').style.display = 'none'; document.getElementById('2401.13058v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 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">12 pages, 12 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 688, A170 (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/2312.11655">arXiv:2312.11655</a> <span> [<a href="https://arxiv.org/pdf/2312.11655">pdf</a>, <a href="https://arxiv.org/format/2312.11655">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"> X-Ray Polarimetry of the Dipping Accreting Neutron Star 4U 1624-49 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Saade%2C+M+L">M. Lynne Saade</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">Philip Kaaret</a>, <a href="/search/astro-ph?searchtype=author&query=Gnarini%2C+A">Andrea Gnarini</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Ursini%2C+F">Francesco Ursini</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">Stefano Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Bobrikova%2C+A">Anna Bobrikova</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=Capitanio%2C+F">Fiamma Capitanio</a>, <a href="/search/astro-ph?searchtype=author&query=Veledina%2C+A">Alexandra Veledina</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Ivan Agudo</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=Bongiorno%2C+S+D">Stephen D. Bongiorno</a>, <a href="/search/astro-ph?searchtype=author&query=Bonino%2C+R">Raffaella Bonino</a>, <a href="/search/astro-ph?searchtype=author&query=Brez%2C+A">Alessandro Brez</a>, <a href="/search/astro-ph?searchtype=author&query=Bucciantini%2C+N">Niccolo Bucciantini</a>, <a href="/search/astro-ph?searchtype=author&query=Castellano%2C+S">Simone Castellano</a>, <a href="/search/astro-ph?searchtype=author&query=Cavazzuti%2C+E">Elisabetta Cavazzuti</a>, <a href="/search/astro-ph?searchtype=author&query=Chen%2C+C">Chien-Ting Chen</a>, <a href="/search/astro-ph?searchtype=author&query=Ciprini%2C+S">Stefano Ciprini</a> , et al. (76 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="2312.11655v3-abstract-short" style="display: inline;"> We present the first X-ray polarimetric study of the dipping accreting neutron star 4U 1624$-$49 with the Imaging X-ray Polarimetry Explorer (IXPE). We report a detection of polarization in the non-dip time intervals with a confidence level of 99.99%. We find an average polarization degree (PD) of $3.1\pm0.7$% and a polarization angle of $81\pm6$ degrees east of north in the 2-8 keV band. We repor… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.11655v3-abstract-full').style.display = 'inline'; document.getElementById('2312.11655v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.11655v3-abstract-full" style="display: none;"> We present the first X-ray polarimetric study of the dipping accreting neutron star 4U 1624$-$49 with the Imaging X-ray Polarimetry Explorer (IXPE). We report a detection of polarization in the non-dip time intervals with a confidence level of 99.99%. We find an average polarization degree (PD) of $3.1\pm0.7$% and a polarization angle of $81\pm6$ degrees east of north in the 2-8 keV band. We report an upper limit on the PD of 22% during the X-ray dips with 95% confidence. The PD increases with energy, reaching from $3.0\pm0.9$% in the 4-6 keV band to $6\pm2$% in the 6-8 keV band. This indicates the polarization likely arises from Comptonization. The high PD observed is unlikely to be produced by Comptonization in the boundary layer or spreading layer alone. It can be produced by the addition of an extended geometrically thin slab corona covering part of the accretion disk, as assumed in previous models of dippers, and/or a reflection component from the accretion disk. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.11655v3-abstract-full').style.display = 'none'; document.getElementById('2312.11655v3-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 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 18 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </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/2311.16313">arXiv:2311.16313</a> <span> [<a href="https://arxiv.org/pdf/2311.16313">pdf</a>, <a href="https://arxiv.org/format/2311.16313">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"> X-ray Polarization of the Eastern Lobe of SS 433 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">Philip Kaaret</a>, <a href="/search/astro-ph?searchtype=author&query=Ferrazzoli%2C+R">Riccardo Ferrazzoli</a>, <a href="/search/astro-ph?searchtype=author&query=Silvestri%2C+S">Stefano Silvestri</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Manfreda%2C+A">Alberto Manfreda</a>, <a href="/search/astro-ph?searchtype=author&query=Wu%2C+K">Kinwah Wu</a>, <a href="/search/astro-ph?searchtype=author&query=Costa%2C+E">Enrico Costa</a>, <a href="/search/astro-ph?searchtype=author&query=Soffitta%2C+P">Paolo Soffitta</a>, <a href="/search/astro-ph?searchtype=author&query=Safi-Harb%2C+S">Samar Safi-Harb</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Veledina%2C+A">Alexandra Veledina</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=Slane%2C+P">Patrick Slane</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">Stefano Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Ingram%2C+A">Adam Ingram</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=Cibrario%2C+N">Nicolo Cibrario</a>, <a href="/search/astro-ph?searchtype=author&query=Mac+Intyre%2C+B">Brydyn Mac Intyre</a>, <a href="/search/astro-ph?searchtype=author&query=Mikusincova%2C+R">Romana Mikusincova</a>, <a href="/search/astro-ph?searchtype=author&query=Ratheesh%2C+A">Ajay Ratheesh</a>, <a href="/search/astro-ph?searchtype=author&query=Steiner%2C+J+F">James F. Steiner</a>, <a href="/search/astro-ph?searchtype=author&query=Svoboda%2C+J">Jiri Svoboda</a>, <a href="/search/astro-ph?searchtype=author&query=Tugliani%2C+S">Stefano Tugliani</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Ivan Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Antonelli%2C+L+A">Lucio A. Antonelli</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="2311.16313v1-abstract-short" style="display: inline;"> How astrophysical systems translate the kinetic energy of bulk motion into the acceleration of particles to very high energies is a pressing question. SS 433 is a microquasar that emits TeV gamma-rays indicating the presence of high-energy particles. A region of hard X-ray emission in the eastern lobe of SS 433 was recently identified as an acceleration site. We observed this region with the Imagi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.16313v1-abstract-full').style.display = 'inline'; document.getElementById('2311.16313v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.16313v1-abstract-full" style="display: none;"> How astrophysical systems translate the kinetic energy of bulk motion into the acceleration of particles to very high energies is a pressing question. SS 433 is a microquasar that emits TeV gamma-rays indicating the presence of high-energy particles. A region of hard X-ray emission in the eastern lobe of SS 433 was recently identified as an acceleration site. We observed this region with the Imaging X-ray Polarimetry Explorer and measured a polarization degree in the range 38% to 77%. The high polarization degree indicates the magnetic field has a well ordered component if the X-rays are due to synchrotron emission. The polarization angle is in the range -12 to +10 degrees (east of north) which indicates that the magnetic field is parallel to the jet. Magnetic fields parallel to the bulk flow have also been found in supernova remnants and the jets of powerful radio galaxies. This may be caused by interaction of the flow with the ambient medium. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.16313v1-abstract-full').style.display = 'none'; document.getElementById('2311.16313v1-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 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">8 pages, accepted in the Astrophysical Journal Letters</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2311.06359">arXiv:2311.06359</a> <span> [<a href="https://arxiv.org/pdf/2311.06359">pdf</a>, <a href="https://arxiv.org/format/2311.06359">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/ad132d">10.3847/2041-8213/ad132d <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Highly Significant Detection of X-Ray Polarization from the Brightest Accreting Neutron Star Sco X-1 </p> <p class="authors"> <span class="search-hit">Authors:</span> <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=Bachetti%2C+M">Matteo Bachetti</a>, <a href="/search/astro-ph?searchtype=author&query=Motta%2C+S+E">Sara E. Motta</a>, <a href="/search/astro-ph?searchtype=author&query=Papitto%2C+A">Alessandro Papitto</a>, <a href="/search/astro-ph?searchtype=author&query=Pilia%2C+M">Maura Pilia</a>, <a href="/search/astro-ph?searchtype=author&query=Xie%2C+F">Fei Xie</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">Stefano Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Bobrikova%2C+A">Anna Bobrikova</a>, <a href="/search/astro-ph?searchtype=author&query=Costa%2C+E">Enrico Costa</a>, <a href="/search/astro-ph?searchtype=author&query=Deng%2C+W">Wei Deng</a>, <a href="/search/astro-ph?searchtype=author&query=Ge%2C+M">Mingyu Ge</a>, <a href="/search/astro-ph?searchtype=author&query=Illiano%2C+G">Giulia Illiano</a>, <a href="/search/astro-ph?searchtype=author&query=Jia%2C+S">Shu-Mei Jia</a>, <a href="/search/astro-ph?searchtype=author&query=Krawczynski%2C+H">Henric Krawczynski</a>, <a href="/search/astro-ph?searchtype=author&query=Lai%2C+E+V">Eleonora V. Lai</a>, <a href="/search/astro-ph?searchtype=author&query=Liu%2C+K">Kuan Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Mastroserio%2C+G">Guglielmo Mastroserio</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Rankin%2C+J">John Rankin</a>, <a href="/search/astro-ph?searchtype=author&query=Soffitta%2C+P">Paolo Soffitta</a>, <a href="/search/astro-ph?searchtype=author&query=Veledina%2C+A">Alexandra Veledina</a>, <a href="/search/astro-ph?searchtype=author&query=Ambrosino%2C+F">Filippo Ambrosino</a>, <a href="/search/astro-ph?searchtype=author&query=Del+Santo%2C+M">Melania Del Santo</a> , et al. (94 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="2311.06359v3-abstract-short" style="display: inline;"> The Imaging X-ray Polarimetry Explorer (IXPE) measured with high significance the X-ray polarization of the brightest Z-source Scorpius X-1, resulting in the nominal 2-8 keV energy band in a polarization degree of 1.0(0.2)% and a polarization angle of 8(6)掳 at 90% of confidence level. This observation was strictly simultaneous with observations performed by NICER, NuSTAR, and Insight-HXMT, which a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.06359v3-abstract-full').style.display = 'inline'; document.getElementById('2311.06359v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.06359v3-abstract-full" style="display: none;"> The Imaging X-ray Polarimetry Explorer (IXPE) measured with high significance the X-ray polarization of the brightest Z-source Scorpius X-1, resulting in the nominal 2-8 keV energy band in a polarization degree of 1.0(0.2)% and a polarization angle of 8(6)掳 at 90% of confidence level. This observation was strictly simultaneous with observations performed by NICER, NuSTAR, and Insight-HXMT, which allowed for a precise characterization of its broad-band spectrum from soft to hard X-rays. The source has been observed mainly in its soft state, with short periods of flaring. We also observed low-frequency quasi-periodic oscillations. From a spectro-polarimetric analysis, we associate a polarization to the accretion disk at <3.2% at 90% of confidence level, compatible with expectations for an electron-scattering dominated optically thick atmosphere at the Sco X-1 inclination of 44掳; for the higher-energy Comptonized component, we obtain a polarization of 1.3(0.4)%, in agreement with expectations for a slab of Thomson optical depth of ~7 and an electron temperature of ~3 keV. A polarization rotation with respect to previous observations by OSO-8 and PolarLight, and also with respect to the radio-jet position angle, is observed. This result may indicate a variation of the polarization with the source state that can be related to relativistic precession or to a change in the corona geometry with the accretion flow. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.06359v3-abstract-full').style.display = 'none'; document.getElementById('2311.06359v3-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 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 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">Journal ref:</span> ApJL 960 L11 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2311.05497">arXiv:2311.05497</a> <span> [<a href="https://arxiv.org/pdf/2311.05497">pdf</a>, <a href="https://arxiv.org/format/2311.05497">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"> Tracking the X-ray Polarization of the Black Hole Transient Swift J1727.8-1613 during a State Transition </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ingram%2C+A">Adam Ingram</a>, <a href="/search/astro-ph?searchtype=author&query=Bollemeijer%2C+N">Niek Bollemeijer</a>, <a href="/search/astro-ph?searchtype=author&query=Veledina%2C+A">Alexandra Veledina</a>, <a href="/search/astro-ph?searchtype=author&query=Dovciak%2C+M">Michal Dovciak</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Egron%2C+E">Elise Egron</a>, <a href="/search/astro-ph?searchtype=author&query=Russell%2C+T+D">Thomas D. Russell</a>, <a href="/search/astro-ph?searchtype=author&query=Trushkin%2C+S+A">Sergei A. Trushkin</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Ratheesh%2C+A">Ajay Ratheesh</a>, <a href="/search/astro-ph?searchtype=author&query=Capitanio%2C+F">Fiamma Capitanio</a>, <a href="/search/astro-ph?searchtype=author&query=Connors%2C+R">Riley Connors</a>, <a href="/search/astro-ph?searchtype=author&query=Neilsen%2C+J">Joseph Neilsen</a>, <a href="/search/astro-ph?searchtype=author&query=Kraus%2C+A">Alexander Kraus</a>, <a href="/search/astro-ph?searchtype=author&query=Iacolina%2C+M+N">Maria Noemi Iacolina</a>, <a href="/search/astro-ph?searchtype=author&query=Pellizzoni%2C+A">Alberto Pellizzoni</a>, <a href="/search/astro-ph?searchtype=author&query=Pilia%2C+M">Maura Pilia</a>, <a href="/search/astro-ph?searchtype=author&query=Carotenuto%2C+F">Francesco Carotenuto</a>, <a href="/search/astro-ph?searchtype=author&query=Matt%2C+G">Giorgio Matt</a>, <a href="/search/astro-ph?searchtype=author&query=Mastroserio%2C+G">Guglielmo Mastroserio</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">Philip Kaaret</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">Stefano Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Garcia%2C+J+A">Javier A. Garcia</a>, <a href="/search/astro-ph?searchtype=author&query=Bachetti%2C+M">Matteo Bachetti</a>, <a href="/search/astro-ph?searchtype=author&query=Wu%2C+K">Kinwah Wu</a> , et al. (98 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="2311.05497v3-abstract-short" style="display: inline;"> We report on an observational campaign on the bright black hole X-ray binary Swift J1727.8$-$1613 centered around five observations by the Imaging X-ray Polarimetry Explorer (IXPE). These observations track for the first time the evolution of the X-ray polarization of a black hole X-ray binary across a hard to soft state transition. The 2--8 keV polarization degree decreased from $\sim$4\% to… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.05497v3-abstract-full').style.display = 'inline'; document.getElementById('2311.05497v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.05497v3-abstract-full" style="display: none;"> We report on an observational campaign on the bright black hole X-ray binary Swift J1727.8$-$1613 centered around five observations by the Imaging X-ray Polarimetry Explorer (IXPE). These observations track for the first time the evolution of the X-ray polarization of a black hole X-ray binary across a hard to soft state transition. The 2--8 keV polarization degree decreased from $\sim$4\% to $\sim$3\% across the five observations, but the polarization angle remained oriented in the North-South direction throughout. Based on observations with the Australia Telescope Compact Array (ATCA), we find that the intrinsic 7.25 GHz radio polarization aligns with the X-ray polarization. Assuming the radio polarization aligns with the jet direction (which can be tested in the future with higher spatial resolution images of the jet), our results imply that the X-ray corona is extended in the disk plane, rather than along the jet axis, for the entire hard intermediate state. This in turn implies that the long ($\gtrsim$10 ms) soft lags that we measure with the Neutron star Interior Composition ExploreR (NICER) are dominated by processes other than pure light-crossing delays. Moreover, we find that the evolution of the soft lag amplitude with spectral state does not follow the trend seen for other sources, implying that Swift J1727.8$-$1613 is a member of a hitherto under-sampled sub-population. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.05497v3-abstract-full').style.display = 'none'; document.getElementById('2311.05497v3-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 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 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">Accepted for publication in ApJ. 21 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/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/2311.03667">arXiv:2311.03667</a> <span> [<a href="https://arxiv.org/pdf/2311.03667">pdf</a>, <a href="https://arxiv.org/format/2311.03667">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"> X-ray Polarization Reveals the Precessions of the Neutron Star in Hercules X-1 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Heyl%2C+J">Jeremy Heyl</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">Victor Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Gonz%C3%A1lez-Caniulef%2C+D">Denis Gonz谩lez-Caniulef</a>, <a href="/search/astro-ph?searchtype=author&query=Caiazzo%2C+I">Ilaria Caiazzo</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Mushtukov%2C+A">Alexander Mushtukov</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=Kirmizibayrak%2C+D">Demet Kirmizibayrak</a>, <a href="/search/astro-ph?searchtype=author&query=Bachetti%2C+M">Matteo Bachetti</a>, <a href="/search/astro-ph?searchtype=author&query=Pavlov%2C+G+G">George G. Pavlov</a>, <a href="/search/astro-ph?searchtype=author&query=Forsblom%2C+S+V">Sofia V. Forsblom</a>, <a href="/search/astro-ph?searchtype=author&query=Malacaria%2C+C">Christian Malacaria</a>, <a href="/search/astro-ph?searchtype=author&query=Suleimanov%2C+V+F">Valery F. Suleimanov</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 Angelo Antonelli</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>, <a href="/search/astro-ph?searchtype=author&query=Brez%2C+A">Alessandro Brez</a>, <a href="/search/astro-ph?searchtype=author&query=Bucciantini%2C+N">Niccol貌 Bucciantini</a>, <a href="/search/astro-ph?searchtype=author&query=Capitanio%2C+F">Fiamma Capitanio</a>, <a href="/search/astro-ph?searchtype=author&query=Castellano%2C+S">Simone Castellano</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="2311.03667v1-abstract-short" style="display: inline;"> In an accreting X-ray pulsar, a neutron star accretes matter from a stellar companion through an accretion disk. The high magnetic field of the rotating neutron star disrupts the inner edge of the disc, funneling the gas to flow onto the magnetic poles on its surface. Hercules X-1 is in many ways the prototypical X-ray pulsar; it shows persistent X-ray emission and it resides with its companion HZ… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.03667v1-abstract-full').style.display = 'inline'; document.getElementById('2311.03667v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.03667v1-abstract-full" style="display: none;"> In an accreting X-ray pulsar, a neutron star accretes matter from a stellar companion through an accretion disk. The high magnetic field of the rotating neutron star disrupts the inner edge of the disc, funneling the gas to flow onto the magnetic poles on its surface. Hercules X-1 is in many ways the prototypical X-ray pulsar; it shows persistent X-ray emission and it resides with its companion HZ Her, a two-solar-mass star, at about 7~kpc from Earth. Its emission varies on three distinct timescales: the neutron star rotates every 1.2~seconds, it is eclipsed by its companion each 1.7~days, and the system exhibits a superorbital period of 35~days which has remained remarkably stable since its discovery. Several lines of evidence point to the source of this variation as the precession of the accretion disc, the precession of the neutron star or both. Despite the many hints over the past fifty years, the precession of the neutron star itself has yet not been confirmed or refuted. We here present X-ray polarization measurements with the Imaging X-ray Polarimetry Explorer (IXPE) which probe the spin geometry of the neutron star. These observations provide direct evidence that the 35-day-period is set by the free precession of the neutron star crust, which has the important implication that its crust is somewhat asymmetric fractionally by a few parts per ten million. Furthermore, we find indications that the basic spin geometry of the neutron star is altered by torques on timescale of a few hundred days. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.03667v1-abstract-full').style.display = 'none'; document.getElementById('2311.03667v1-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 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">37 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/2311.03637">arXiv:2311.03637</a> <span> [<a href="https://arxiv.org/pdf/2311.03637">pdf</a>, <a href="https://arxiv.org/format/2311.03637">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 detection of polarized x-ray emission from the magnetar 1E 2259+586 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Heyl%2C+J">Jeremy Heyl</a>, <a href="/search/astro-ph?searchtype=author&query=Taverna%2C+R">Roberto Taverna</a>, <a href="/search/astro-ph?searchtype=author&query=Turolla%2C+R">Roberto Turolla</a>, <a href="/search/astro-ph?searchtype=author&query=Israel%2C+G+L">Gian Luca Israel</a>, <a href="/search/astro-ph?searchtype=author&query=Ng%2C+M">Mason Ng</a>, <a href="/search/astro-ph?searchtype=author&query=Kirmizibayrak%2C+D">Demet Kirmizibayrak</a>, <a href="/search/astro-ph?searchtype=author&query=Gonz%C3%A1lez-Caniulef%2C+D">Denis Gonz谩lez-Caniulef</a>, <a href="/search/astro-ph?searchtype=author&query=Caiazzo%2C+I">Ilaria Caiazzo</a>, <a href="/search/astro-ph?searchtype=author&query=Zane%2C+S">Silvia Zane</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=Negro%2C+M">Michela Negro</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 Angelo 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>, <a href="/search/astro-ph?searchtype=author&query=Brez%2C+A">Alessandro Brez</a>, <a href="/search/astro-ph?searchtype=author&query=Bucciantini%2C+N">Niccol貌 Bucciantini</a>, <a href="/search/astro-ph?searchtype=author&query=Capitanio%2C+F">Fiamma Capitanio</a>, <a href="/search/astro-ph?searchtype=author&query=Castellano%2C+S">Simone Castellano</a>, <a href="/search/astro-ph?searchtype=author&query=Cavazzuti%2C+E">Elisabetta Cavazzuti</a> , et al. (76 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="2311.03637v1-abstract-short" style="display: inline;"> We report on IXPE, NICER and XMM-Newton observations of the magnetar 1E 2259+586. We find that the source is significantly polarized at about or above 20% for all phases except for the secondary peak where it is more weakly polarized. The polarization degree is strongest during the primary minimum which is also the phase where an absorption feature has been identified previously (Pizzocaro et al.… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.03637v1-abstract-full').style.display = 'inline'; document.getElementById('2311.03637v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2311.03637v1-abstract-full" style="display: none;"> We report on IXPE, NICER and XMM-Newton observations of the magnetar 1E 2259+586. We find that the source is significantly polarized at about or above 20% for all phases except for the secondary peak where it is more weakly polarized. The polarization degree is strongest during the primary minimum which is also the phase where an absorption feature has been identified previously (Pizzocaro et al. 2019). The polarization angle of the photons are consistent with a rotating vector model with a mode switch between the primary minimum and the rest of the rotation of the neutron star. We propose a scenario in which the emission at the source is weakly polarized (as in a condensed surface) and, as the radiation passes through a plasma arch, resonant cyclotron scattering off of protons produces the observed polarized radiation. This confirms the magnetar nature of the source with a surface field greater than about 10<sup>15</sup> G <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2311.03637v1-abstract-full').style.display = 'none'; document.getElementById('2311.03637v1-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 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">13 pages, 13 figures, 5 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/2310.20196">arXiv:2310.20196</a> <span> [<a href="https://arxiv.org/pdf/2310.20196">pdf</a>, <a href="https://arxiv.org/ps/2310.20196">ps</a>, <a href="https://arxiv.org/format/2310.20196">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"> Further Development of Event-Based Analysis of X-ray Polarization Data </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> </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="2310.20196v2-abstract-short" style="display: inline;"> An event-based maximum likelihood method for handling X-ray polarimetry data is extended to include the effects of background and nonuniform sampling of the possible position angle space. While nonuniform sampling in position angle space generally introduces cross terms in the uncertainties of polarization parameters that could create degeneracies, there are interesting cases that engender no bias… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.20196v2-abstract-full').style.display = 'inline'; document.getElementById('2310.20196v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.20196v2-abstract-full" style="display: none;"> An event-based maximum likelihood method for handling X-ray polarimetry data is extended to include the effects of background and nonuniform sampling of the possible position angle space. While nonuniform sampling in position angle space generally introduces cross terms in the uncertainties of polarization parameters that could create degeneracies, there are interesting cases that engender no bias or parameter covariance. When including background in Poisson-based likelihood formulation, the formula for the minimum detectable polarization (MDP) has nearly the same form as for the case of Gaussian statistics derived by Elsner et al. (2012) in the limiting case of an unpolarized signal. A polarized background is also considered, which demonstrably increases uncertainties in source polarization measurements. In addition, a Kolmogorov-style test of the event position angle distribution is proposed that can provide an unbinned test of models where the polarization angle in Stokes space depends on event characteristics such as time or energy. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.20196v2-abstract-full').style.display = 'none'; document.getElementById('2310.20196v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 31 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">8 pages, accepted for publication in the Astrophysical Journal. This version contains several modifications to various equations and a "note added in proof"</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.11510">arXiv:2310.11510</a> <span> [<a href="https://arxiv.org/pdf/2310.11510">pdf</a>, <a href="https://arxiv.org/format/2310.11510">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Observations of Low and Intermediate Spectral Peak Blazars with the Imaging X-ray Polarimetry Explorer </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Lalla%2C+N">Niccolo Di Lalla</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Omodei%2C+N">Nicola Omodei</a>, <a href="/search/astro-ph?searchtype=author&query=Peirson%2C+A+L">Abel L. Peirson</a>, <a href="/search/astro-ph?searchtype=author&query=Perri%2C+M">Matteo Perri</a>, <a href="/search/astro-ph?searchtype=author&query=Puccetti%2C+S">Simonetta Puccetti</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Ivan Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">Giacomo Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Berdyugin%2C+A+V">Andrei V. Berdyugin</a>, <a href="/search/astro-ph?searchtype=author&query=Cavazzuti%2C+E">Elisabetta Cavazzuti</a>, <a href="/search/astro-ph?searchtype=author&query=Cavero%2C+N+R">Nicole Rodriguez Cavero</a>, <a href="/search/astro-ph?searchtype=author&query=Donnarumma%2C+I">Immacolata Donnarumma</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Jormanainen%2C+J">Jenni Jormanainen</a>, <a href="/search/astro-ph?searchtype=author&query=Krawczynski%2C+H">Henric Krawczynski</a>, <a href="/search/astro-ph?searchtype=author&query=Lindfors%2C+E">Elina Lindfors</a>, <a href="/search/astro-ph?searchtype=author&query=Marin%2C+F">Frederic Marin</a>, <a href="/search/astro-ph?searchtype=author&query=Massaro%2C+F">Francesco Massaro</a>, <a href="/search/astro-ph?searchtype=author&query=Pacciani%2C+L">Luigi Pacciani</a> , et al. (133 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2310.11510v2-abstract-short" style="display: inline;"> We present X-ray polarimetry observations from the Imaging X-ray Polarimetry Explorer (IXPE) of three low spectral peak and one intermediate spectral peak blazars, namely 3C 273, 3C 279, 3C 454.3, and S5 0716+714. For none of these objects was IXPE able to detect X-ray polarization at the 3$蟽$ level. However, we placed upper limits on the polarization degree at $\sim$10-30\%. The undetected polari… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.11510v2-abstract-full').style.display = 'inline'; document.getElementById('2310.11510v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.11510v2-abstract-full" style="display: none;"> We present X-ray polarimetry observations from the Imaging X-ray Polarimetry Explorer (IXPE) of three low spectral peak and one intermediate spectral peak blazars, namely 3C 273, 3C 279, 3C 454.3, and S5 0716+714. For none of these objects was IXPE able to detect X-ray polarization at the 3$蟽$ level. However, we placed upper limits on the polarization degree at $\sim$10-30\%. The undetected polarizations favor models where the X-ray band is dominated by unpolarized photons upscattered by relativistic electrons in the jets of blazars, although hadronic models are not completely eliminated. We discuss the X-ray polarization upper limits in the context of our contemporaneous multiwavelength polarization campaigns. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.11510v2-abstract-full').style.display = 'none'; document.getElementById('2310.11510v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 10 figures, 6 tables; submitted to the Astrophysical Journal</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.11125">arXiv:2310.11125</a> <span> [<a href="https://arxiv.org/pdf/2310.11125">pdf</a>, <a href="https://arxiv.org/format/2310.11125">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 confirms a high spin in the accreting black hole 4U 1957+115 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Marra%2C+L">L. Marra</a>, <a href="/search/astro-ph?searchtype=author&query=Brigitte%2C+M">M. Brigitte</a>, <a href="/search/astro-ph?searchtype=author&query=Cavero%2C+N+R">N. Rodriguez Cavero</a>, <a href="/search/astro-ph?searchtype=author&query=Chun%2C+S">S. Chun</a>, <a href="/search/astro-ph?searchtype=author&query=Steiner%2C+J+F">J. F. Steiner</a>, <a href="/search/astro-ph?searchtype=author&query=Dov%C4%8Diak%2C+M">M. Dov膷iak</a>, <a href="/search/astro-ph?searchtype=author&query=Nowak%2C+M">M. Nowak</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">S. Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Capitanio%2C+F">F. Capitanio</a>, <a href="/search/astro-ph?searchtype=author&query=Ingram%2C+A">A. Ingram</a>, <a href="/search/astro-ph?searchtype=author&query=Matt%2C+G">G. Matt</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">F. Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Podgorn%C3%BD%2C+J">J. Podgorn媒</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">J. Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Svoboda%2C+J">J. Svoboda</a>, <a href="/search/astro-ph?searchtype=author&query=Taverna%2C+R">R. Taverna</a>, <a href="/search/astro-ph?searchtype=author&query=Ursini%2C+F">F. Ursini</a>, <a href="/search/astro-ph?searchtype=author&query=Veledina%2C+A">A. Veledina</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=Garcia%2C+J+A">J. A. Garcia</a>, <a href="/search/astro-ph?searchtype=author&query=Lutovinov%2C+A+A">A. A. Lutovinov</a>, <a href="/search/astro-ph?searchtype=author&query=Mereminskiy%2C+I+A">I. A. Mereminskiy</a>, <a href="/search/astro-ph?searchtype=author&query=Farinelli%2C+R">R. Farinelli</a>, <a href="/search/astro-ph?searchtype=author&query=Gunji%2C+S">S. Gunji</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">P. Kaaret</a> , et al. (91 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="2310.11125v2-abstract-short" style="display: inline;"> We present the results of the first X-ray polarimetric observation of the low-mass X-ray binary 4U 1957+115, performed with the Imaging X-ray Polarimetry Explorer in May 2023. The binary system has been in a high-soft spectral state since its discovery and is thought to host a black hole. The $\sim$571 ks observation reveals a linear polarisation degree of $1.9\% \pm 0.6\%$ and a polarisation angl… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.11125v2-abstract-full').style.display = 'inline'; document.getElementById('2310.11125v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.11125v2-abstract-full" style="display: none;"> We present the results of the first X-ray polarimetric observation of the low-mass X-ray binary 4U 1957+115, performed with the Imaging X-ray Polarimetry Explorer in May 2023. The binary system has been in a high-soft spectral state since its discovery and is thought to host a black hole. The $\sim$571 ks observation reveals a linear polarisation degree of $1.9\% \pm 0.6\%$ and a polarisation angle of $-41^\circ.8 \pm 7^\circ.9$ in the 2-8 keV energy range. Spectral modelling is consistent with the dominant contribution coming from the standard accretion disc, while polarimetric data suggest a significant role of returning radiation: photons that are bent by strong gravity effects and forced to return to the disc surface, where they can be reflected before eventually reaching the observer. In this setting, we find that models with a black hole spin lower than 0.96 and an inclination lower than $50^\circ$ are disfavoured. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.11125v2-abstract-full').style.display = 'none'; document.getElementById('2310.11125v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 February, 2024; <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">12 pages, 10 figures, 2 tables, accepted for publication in A&A</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.06788">arXiv:2310.06788</a> <span> [<a href="https://arxiv.org/pdf/2310.06788">pdf</a>, <a href="https://arxiv.org/ps/2310.06788">ps</a>, <a href="https://arxiv.org/format/2310.06788">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 a variable energy-dependent X-ray polarization in the accreting neutron star GX 5-1 </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=Capitanio%2C+F">Fiamma Capitanio</a>, <a href="/search/astro-ph?searchtype=author&query=Iaria%2C+R">Rosario Iaria</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Gnarini%2C+A">Andrea Gnarini</a>, <a href="/search/astro-ph?searchtype=author&query=Ursini%2C+F">Francesco Ursini</a>, <a href="/search/astro-ph?searchtype=author&query=Farinelli%2C+R">Ruben Farinelli</a>, <a href="/search/astro-ph?searchtype=author&query=Bobrikova%2C+A">Anna Bobrikova</a>, <a href="/search/astro-ph?searchtype=author&query=Steiner%2C+J+F">James F. Steiner</a>, <a href="/search/astro-ph?searchtype=author&query=Svoboda%2C+J">Jiri Svoboda</a>, <a href="/search/astro-ph?searchtype=author&query=Anitra%2C+A">Alessio Anitra</a>, <a href="/search/astro-ph?searchtype=author&query=Baglio%2C+M+C">Maria C. Baglio</a>, <a href="/search/astro-ph?searchtype=author&query=Carotenuto%2C+F">Francesco Carotenuto</a>, <a href="/search/astro-ph?searchtype=author&query=Del+Santo%2C+M">Melania Del Santo</a>, <a href="/search/astro-ph?searchtype=author&query=Ferrigno%2C+C">Carlo Ferrigno</a>, <a href="/search/astro-ph?searchtype=author&query=Lewis%2C+F">Fraser Lewis</a>, <a href="/search/astro-ph?searchtype=author&query=Russell%2C+D+M">David M. Russell</a>, <a href="/search/astro-ph?searchtype=author&query=Russell%2C+T+D">Thomas D. Russell</a>, <a href="/search/astro-ph?searchtype=author&query=Eijnden%2C+J+v+d">Jakob van den Eijnden</a>, <a href="/search/astro-ph?searchtype=author&query=Cocchi%2C+M">Massimo Cocchi</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=La+Monaca%2C+F">Fabio La Monaca</a>, <a href="/search/astro-ph?searchtype=author&query=Liu%2C+K">Kuan Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Rankin%2C+J">John Rankin</a>, <a href="/search/astro-ph?searchtype=author&query=Weisskopf%2C+M+C">Martin C. Weisskopf</a> , et al. (94 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="2310.06788v2-abstract-short" style="display: inline;"> We report on the coordinated observations of the neutron star low-mass X-ray binary (NS-LMXB) \gx in X-rays (IXPE, NICER, Nustar and INTEGRAL), optical (REM and LCO), near-infrared (REM), mid-infrared (VLT VISIR), and radio (ATCA). This Z-source was observed by \IXPE twice in March-April 2023 (Obs. 1 and 2). In the radio band, the source was detected, but only upper-limits to the linear polarizati… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.06788v2-abstract-full').style.display = 'inline'; document.getElementById('2310.06788v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.06788v2-abstract-full" style="display: none;"> We report on the coordinated observations of the neutron star low-mass X-ray binary (NS-LMXB) \gx in X-rays (IXPE, NICER, Nustar and INTEGRAL), optical (REM and LCO), near-infrared (REM), mid-infrared (VLT VISIR), and radio (ATCA). This Z-source was observed by \IXPE twice in March-April 2023 (Obs. 1 and 2). In the radio band, the source was detected, but only upper-limits to the linear polarization were obtained at a $3蟽$ level of $6.1\%$ at 5.5 GHz and $5.9\%$ at 9 GHz in Obs.~1 and $12.5\%$ at 5.5~GHz and $20\%$ at 9~GHz in Obs.~2. The mid-IR, near-IR and optical observations suggest the presence of a compact jet which peaks in the mid- or far-IR. The X-ray polarization degree was found to be $3.7\% \pm 0.4 \%$ (at $90\%$ confidence level) during Obs.~1 when the source was in the horizontal branch of the Z-track and $1.8\% \pm 0.4 \%$ during Obs.~2 when the source was in the normal-flaring branch. These results confirm the variation of polarization degree as a function of the position of the source in the color-color diagram as for previously observed Z-track sources (Cyg~X-2 and XTE~1701$-$462). Evidence for a variation of the polarization angle $\sim 20^\circ$ with energy is found in both observations, likely related to the different, non-orthogonal polarization angles of the disk and Comptonization components which peak at different energies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.06788v2-abstract-full').style.display = 'none'; document.getElementById('2310.06788v2-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 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 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">Submitted to Astronomy and Astrophysics on 06 July 2023. Accepted on 21 November 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/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/2310.01635">arXiv:2310.01635</a> <span> [<a href="https://arxiv.org/pdf/2310.01635">pdf</a>, <a href="https://arxiv.org/format/2310.01635">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"> X-ray Polarization of the BL Lac Type Blazar 1ES 0229+200 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Ehlert%2C+S+R">Steven R. Ehlert</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=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Tavecchio%2C+F">Fabrizio Tavecchio</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=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=Nilsson%2C+K">Kari Nilsson</a>, <a href="/search/astro-ph?searchtype=author&query=Myserlis%2C+I">Ioannis Myserlis</a>, <a href="/search/astro-ph?searchtype=author&query=Gurwell%2C+M">Mark Gurwell</a>, <a href="/search/astro-ph?searchtype=author&query=Rao%2C+R">Ramprasad Rao</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=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=Agiz-Gonzalez%2C+B">Beatriz Agiz-Gonzalez</a>, <a href="/search/astro-ph?searchtype=author&query=Escudero%2C+J">Juan Escudero</a>, <a href="/search/astro-ph?searchtype=author&query=Santos%2C+J+O">Jorge Otero Santos</a>, <a href="/search/astro-ph?searchtype=author&query=Sota%2C+A">Alfredo Sota</a>, <a href="/search/astro-ph?searchtype=author&query=Angelakis%2C+E">Emmanouil Angelakis</a>, <a href="/search/astro-ph?searchtype=author&query=Kraus%2C+A">Alexander Kraus</a>, <a href="/search/astro-ph?searchtype=author&query=Keating%2C+G+K">Garrett K. Keating</a>, <a href="/search/astro-ph?searchtype=author&query=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> , et al. (88 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="2310.01635v1-abstract-short" style="display: inline;"> We present polarization measurements in the $2-8 \thinspace \mathrm{keV}$ band from blazar 1ES 0229+200, the first extreme high synchrotron peaked source to be observed by the Imaging X-ray Polarimetry Explorer (IXPE). Combining two exposures separated by about two weeks, we find the degree of polarization to be $螤_{X} = 17.9 \pm 2.8 \%$ at an electric-vector position angle… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.01635v1-abstract-full').style.display = 'inline'; document.getElementById('2310.01635v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.01635v1-abstract-full" style="display: none;"> We present polarization measurements in the $2-8 \thinspace \mathrm{keV}$ band from blazar 1ES 0229+200, the first extreme high synchrotron peaked source to be observed by the Imaging X-ray Polarimetry Explorer (IXPE). Combining two exposures separated by about two weeks, we find the degree of polarization to be $螤_{X} = 17.9 \pm 2.8 \%$ at an electric-vector position angle $蠄_X = 25.0 \pm 4.6^{\circ}$ using a spectropolarimetric fit from joint IXPE and XMM-Newton observations. There is no evidence for the polarization degree or angle varying significantly with energy or time on both short time scales (hours) or longer time scales (days). The contemporaneous polarization degree at optical wavelengths was $>$7$\times$ lower, making 1ES 0229+200 the most strongly chromatic blazar yet observed. This high X-ray polarization compared to the optical provides further support that X-ray emission in high-peaked blazars originates in shock-accelerated, energy-stratified electron populations, but is in tension with many recent modeling efforts attempting to reproduce the spectral energy distribution of 1ES 0229+200 which attribute the extremely high energy synchrotron and Compton peaks to Fermi acceleration in the vicinity of strongly turbulent magnetic fields. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.01635v1-abstract-full').style.display = 'none'; document.getElementById('2310.01635v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 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, 6 Figures, Resubmitted to ApJ after addressing referee comments</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/2309.15928">arXiv:2309.15928</a> <span> [<a href="https://arxiv.org/pdf/2309.15928">pdf</a>, <a href="https://arxiv.org/format/2309.15928">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="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> </div> <p class="title is-5 mathjax"> Discovery of X-ray Polarization from the Black Hole Transient Swift J1727.8-1613 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Veledina%2C+A">Alexandra Veledina</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Dovciak%2C+M">Michal Dovciak</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Ratheesh%2C+A">Ajay Ratheesh</a>, <a href="/search/astro-ph?searchtype=author&query=Capitanio%2C+F">Fiamma Capitanio</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=Tennant%2C+A+F">Allyn F. Tennant</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">Philip Kaaret</a>, <a href="/search/astro-ph?searchtype=author&query=Costa%2C+E">Enrico Costa</a>, <a href="/search/astro-ph?searchtype=author&query=Ingram%2C+A">Adam Ingram</a>, <a href="/search/astro-ph?searchtype=author&query=Svoboda%2C+J">Jiri Svoboda</a>, <a href="/search/astro-ph?searchtype=author&query=Krawczynski%2C+H">Henric Krawczynski</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">Stefano Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Steiner%2C+J+F">James F. Steiner</a>, <a href="/search/astro-ph?searchtype=author&query=Garcia%2C+J+A">Javier A. Garcia</a>, <a href="/search/astro-ph?searchtype=author&query=Kravtsov%2C+V">Vadim Kravtsov</a>, <a href="/search/astro-ph?searchtype=author&query=Nitindala%2C+A+P">Anagha P. Nitindala</a>, <a href="/search/astro-ph?searchtype=author&query=Ewing%2C+M">Melissa Ewing</a>, <a href="/search/astro-ph?searchtype=author&query=Mastroserio%2C+G">Guglielmo Mastroserio</a>, <a href="/search/astro-ph?searchtype=author&query=Marinucci%2C+A">Andrea Marinucci</a>, <a href="/search/astro-ph?searchtype=author&query=Ursini%2C+F">Francesco Ursini</a>, <a href="/search/astro-ph?searchtype=author&query=Tombesi%2C+F">Francesco Tombesi</a> , et al. (91 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="2309.15928v1-abstract-short" style="display: inline;"> We report the first detection of the X-ray polarization of the bright transient Swift J1727.8-1613 with the Imaging X-ray Polarimetry Explorer. The observation was performed at the beginning of the 2023 discovery outburst, when the source resided in the bright hard state. We find a time- and energy-averaged polarization degree of 4.1%+/-0.2% and a polarization angle of 2.2+/-1.3 degrees (errors at… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.15928v1-abstract-full').style.display = 'inline'; document.getElementById('2309.15928v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.15928v1-abstract-full" style="display: none;"> We report the first detection of the X-ray polarization of the bright transient Swift J1727.8-1613 with the Imaging X-ray Polarimetry Explorer. The observation was performed at the beginning of the 2023 discovery outburst, when the source resided in the bright hard state. We find a time- and energy-averaged polarization degree of 4.1%+/-0.2% and a polarization angle of 2.2+/-1.3 degrees (errors at 68% confidence level; this translates to about 20-sigma significance of the polarization detection). This finding suggests that the hot corona emitting the bulk of the detected X-rays is elongated, rather than spherical. The X-ray polarization angle is consistent with that found in sub-mm wavelengths. Since the sub-mm polarization was found to be aligned with the jet direction in other X-ray binaries, this indicates that the corona is elongated orthogonal to the jet. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.15928v1-abstract-full').style.display = 'none'; document.getElementById('2309.15928v1-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">10 pages, 3 figures, submitted</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2309.10813">arXiv:2309.10813</a> <span> [<a href="https://arxiv.org/pdf/2309.10813">pdf</a>, <a href="https://arxiv.org/format/2309.10813">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/ad0842">10.3847/1538-4357/ad0842 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> First X-ray polarization measurement confirms the low black-hole spin in LMC X-3 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Svoboda%2C+J">Ji艡铆 Svoboda</a>, <a href="/search/astro-ph?searchtype=author&query=Dov%C4%8Diak%2C+M">Michal Dov膷iak</a>, <a href="/search/astro-ph?searchtype=author&query=Steiner%2C+J+F">James F. Steiner</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Ingram%2C+A">Adam Ingram</a>, <a href="/search/astro-ph?searchtype=author&query=Yilmaz%2C+A">Anastasiya Yilmaz</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=Marra%2C+L">Lorenzo Marra</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Veledina%2C+A">Alexandra Veledina</a>, <a href="/search/astro-ph?searchtype=author&query=Mojaver%2C+M+R">Mehrnoosh Rahbardar Mojaver</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">Stefano Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Garcia%2C+J">Javier Garcia</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">Philip Kaaret</a>, <a href="/search/astro-ph?searchtype=author&query=Krawczynski%2C+H">Henric Krawczynski</a>, <a href="/search/astro-ph?searchtype=author&query=Matt%2C+G">Giorgio Matt</a>, <a href="/search/astro-ph?searchtype=author&query=Podgorn%C3%BD%2C+J">Jakub Podgorn媒</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=Kislat%2C+F">Fabian Kislat</a>, <a href="/search/astro-ph?searchtype=author&query=Petrucci%2C+P">Pierre-Olivier Petrucci</a>, <a href="/search/astro-ph?searchtype=author&query=Brigitte%2C+M">Maimouna Brigitte</a>, <a href="/search/astro-ph?searchtype=author&query=Bursa%2C+M">Michal Bursa</a>, <a href="/search/astro-ph?searchtype=author&query=Fabiani%2C+S">Sergio Fabiani</a>, <a href="/search/astro-ph?searchtype=author&query=Hu%2C+K">Kun Hu</a>, <a href="/search/astro-ph?searchtype=author&query=Chun%2C+S">Sohee Chun</a> , et al. (87 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="2309.10813v1-abstract-short" style="display: inline;"> X-ray polarization is a powerful tool to investigate the geometry of accreting material around black holes, allowing independent measurements of the black hole spin and orientation of the innermost parts of the accretion disk. We perform the X-ray spectro-polarimetric analysis of an X-ray binary system in the Large Magellanic Cloud, LMC X-3, that hosts a stellar-mass black hole, known to be persis… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.10813v1-abstract-full').style.display = 'inline'; document.getElementById('2309.10813v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2309.10813v1-abstract-full" style="display: none;"> X-ray polarization is a powerful tool to investigate the geometry of accreting material around black holes, allowing independent measurements of the black hole spin and orientation of the innermost parts of the accretion disk. We perform the X-ray spectro-polarimetric analysis of an X-ray binary system in the Large Magellanic Cloud, LMC X-3, that hosts a stellar-mass black hole, known to be persistently accreting since its discovery. We report the first detection of the X-ray polarization in LMC X-3 with the Imaging X-ray Polarimetry Explorer, and find the average polarization degree of 3.2% +- 0.6% and a constant polarization angle -42 deg +- 6 deg over the 2-8 keV range. Using accompanying spectroscopic observations by NICER, NuSTAR, and the Neil Gehrels Swift observatories, we confirm previous measurements of the black hole spin via the X-ray continuum method, a ~ 0.2. From polarization analysis only, we found consistent results with low black-hole spin, with an upper limit of a < 0.7 at a 90% confidence level. A slight increase of the polarization degree with energy, similar to other black-hole X-ray binaries in the soft state, is suggested from the data but with a low statistical significance. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2309.10813v1-abstract-full').style.display = 'none'; document.getElementById('2309.10813v1-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 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">14 pages, 8 figures, submitted to ApJ</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> The Astrophysical Journal, 2024, 960, 3 </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/2308.01238">arXiv:2308.01238</a> <span> [<a href="https://arxiv.org/pdf/2308.01238">pdf</a>, <a href="https://arxiv.org/format/2308.01238">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> </div> <p class="title is-5 mathjax"> IXPE and XMM-Newton observations of the Soft Gamma Repeater SGR 1806-20 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Turolla%2C+R">Roberto Turolla</a>, <a href="/search/astro-ph?searchtype=author&query=Taverna%2C+R">Roberto Taverna</a>, <a href="/search/astro-ph?searchtype=author&query=Israel%2C+G+L">Gian Luca Israel</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Zane%2C+S">Silvia Zane</a>, <a href="/search/astro-ph?searchtype=author&query=Bachetti%2C+M">Matteo Bachetti</a>, <a href="/search/astro-ph?searchtype=author&query=Heyl%2C+J">Jeremy Heyl</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=Gau%2C+E">Ephraim Gau</a>, <a href="/search/astro-ph?searchtype=author&query=Krawczynski%2C+H">Henric Krawczynski</a>, <a href="/search/astro-ph?searchtype=author&query=Ng%2C+M">Mason Ng</a>, <a href="/search/astro-ph?searchtype=author&query=Possenti%2C+A">Andrea Possenti</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Baldini%2C+L">Luca Baldini</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=Agudo%2C+I">Ivan Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Antonelli%2C+L+A">Lucio Angelo Antonelli</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>, <a href="/search/astro-ph?searchtype=author&query=Brez%2C+A">Alessandro Brez</a>, <a href="/search/astro-ph?searchtype=author&query=Bucciantini%2C+N">Niccolo' Bucciantini</a> , et al. (74 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2308.01238v1-abstract-short" style="display: inline;"> Recent observations with the Imaging X-ray Polarimetry Explorer (IXPE) of two anomalous X-ray pulsars provided evidence that X-ray emission from magnetar sources is strongly polarized. Here we report on the joint IXPE and XMM-Newton observations of the soft 纬-repeater SGR 1806-20. The spectral and timing properties of SGR 1806-20 derived from XMM-Newton data are in broad agreement with previous me… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.01238v1-abstract-full').style.display = 'inline'; document.getElementById('2308.01238v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.01238v1-abstract-full" style="display: none;"> Recent observations with the Imaging X-ray Polarimetry Explorer (IXPE) of two anomalous X-ray pulsars provided evidence that X-ray emission from magnetar sources is strongly polarized. Here we report on the joint IXPE and XMM-Newton observations of the soft 纬-repeater SGR 1806-20. The spectral and timing properties of SGR 1806-20 derived from XMM-Newton data are in broad agreement with previous measurements; however, we found the source at an all-time-low persistent flux level. No significant polarization was measured apart from the 4-5 keV energy range, where a probable detection with PD=31.6\pm 10.5% and PA=-17.6\pm 15 deg was obtained. The resulting polarization signal, together with the upper limits we derive at lower and higher energies 2-4 and 5-8 keV, respectively) is compatible with a picture in which thermal radiation from the condensed star surface is reprocessed by resonant Compton scattering in the magnetosphere, similar to what proposed for the bright magnetar 4U 0142+61. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.01238v1-abstract-full').style.display = 'none'; document.getElementById('2308.01238v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 2 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 3 figures, accepted for publication in ApJ</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/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/2306.10965">arXiv:2306.10965</a> <span> [<a href="https://arxiv.org/pdf/2306.10965">pdf</a>, <a href="https://arxiv.org/format/2306.10965">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="Solar and Stellar Astrophysics">astro-ph.SR</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/10.1051/0004-6361/202346275">10.1051/0004-6361/202346275 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Discovery of strongly variable X-ray polarization in the neutron star low-mass X-ray binary transient XTE J1701$-$462 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Cocchi%2C+M">Massimo Cocchi</a>, <a href="/search/astro-ph?searchtype=author&query=Gnarini%2C+A">Andrea Gnarini</a>, <a href="/search/astro-ph?searchtype=author&query=Fabiani%2C+S">Sergio Fabiani</a>, <a href="/search/astro-ph?searchtype=author&query=Ursini%2C+F">Francesco Ursini</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Capitanio%2C+F">Fiamma Capitanio</a>, <a href="/search/astro-ph?searchtype=author&query=Bobrikova%2C+A">Anna Bobrikova</a>, <a href="/search/astro-ph?searchtype=author&query=Farinelli%2C+R">Ruben Farinelli</a>, <a href="/search/astro-ph?searchtype=author&query=Paizis%2C+A">Adamantia Paizis</a>, <a href="/search/astro-ph?searchtype=author&query=Sidoli%2C+L">Lara Sidoli</a>, <a href="/search/astro-ph?searchtype=author&query=Veledina%2C+A">Alexandra Veledina</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">Stefano Bianchi</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=Ingram%2C+A">Adam Ingram</a>, <a href="/search/astro-ph?searchtype=author&query=Kajava%2C+J+J+E">Jari J. E. Kajava</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=Matt%2C+G">Giorgio Matt</a>, <a href="/search/astro-ph?searchtype=author&query=Malacaria%2C+C">Christian Malacaria</a>, <a href="/search/astro-ph?searchtype=author&query=Miku%C5%A1incov%C3%A1%2C+R">Romana Miku拧incov谩</a>, <a href="/search/astro-ph?searchtype=author&query=Rankin%2C+J">John Rankin</a>, <a href="/search/astro-ph?searchtype=author&query=Zane%2C+S">Silvia Zane</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>, <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> , 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="2306.10965v1-abstract-short" style="display: inline;"> After about 16 years since its first outburst, the transient neutron star low-mass X-ray binary XTE J1701$-$462 turned on again in September 2022, allowing for the first study of its X-ray polarimetric characteristics by a dedicated observing program with the Imaging X-ray Polarimeter Explorer (IXPE). Polarimetric studies of XTE J1701$-$462 have been expected to improve our understanding of accret… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.10965v1-abstract-full').style.display = 'inline'; document.getElementById('2306.10965v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.10965v1-abstract-full" style="display: none;"> After about 16 years since its first outburst, the transient neutron star low-mass X-ray binary XTE J1701$-$462 turned on again in September 2022, allowing for the first study of its X-ray polarimetric characteristics by a dedicated observing program with the Imaging X-ray Polarimeter Explorer (IXPE). Polarimetric studies of XTE J1701$-$462 have been expected to improve our understanding of accreting weakly magnetized neutron stars, in particular, the physics and the geometry of the hot inner regions close to the compact object. The IXPE data of two triggered observations were analyzed using time-resolved spectroscopic and polarimetric techniques, following the source along its Z-track of the color-color diagram. During the first pointing on 2022 September 29, an average 2-8 keV polarization degree of 4.6$\pm$ 0.4\% was measured, the highest value found up to now for this class of sources. Conversely, only a $\sim$0.6\% average degree was obtained during the second pointing ten days later. The polarimetric signal appears to be strictly related to the higher energy blackbody component associated with the boundary layer (BL) emission and its reflection from the inner accretion disk, and it is as strong as 6.1\% and 1.2\% ($>95\%$ significant) above 3-4 keV for the two measurements, respectively. The variable polarimetric signal is apparently related to the spectral characteristics of XTE J1701$-$462, which is the strongest when the source was in the horizontal branch of its Z-track and the weakest in the normal branch. These IXPE results provide new important observational constraints on the physical models and geometry of the Z-sources. Here, we discuss the possible reasons for the presence of strong and variable polarization among these sources. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.10965v1-abstract-full').style.display = 'none'; document.getElementById('2306.10965v1-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 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 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">7 pages, 8 figures; published in A&A 674, L10 (2023)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 674, L10 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.08476">arXiv:2306.08476</a> <span> [<a href="https://arxiv.org/pdf/2306.08476">pdf</a>, <a href="https://arxiv.org/format/2306.08476">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/acec6e">10.3847/2041-8213/acec6e <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> First detection of X-ray polarization from the accreting neutron star 4U 1820-303 </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=La+Monaca%2C+F">Fabio La Monaca</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Russell%2C+T+D">Thomas D. Russell</a>, <a href="/search/astro-ph?searchtype=author&query=Anitra%2C+A">Alessio Anitra</a>, <a href="/search/astro-ph?searchtype=author&query=Farinelli%2C+R">Ruben Farinelli</a>, <a href="/search/astro-ph?searchtype=author&query=Mastroserio%2C+G">Guglielmo Mastroserio</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Xie%2C+F">Fei Xie</a>, <a href="/search/astro-ph?searchtype=author&query=Bachetti%2C+M">Matteo Bachetti</a>, <a href="/search/astro-ph?searchtype=author&query=Burderi%2C+L">Luciano Burderi</a>, <a href="/search/astro-ph?searchtype=author&query=Carotenuto%2C+F">Francesco Carotenuto</a>, <a href="/search/astro-ph?searchtype=author&query=Del+Santo%2C+M">Melania Del Santo</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Salvo%2C+T">Tiziana Di Salvo</a>, <a href="/search/astro-ph?searchtype=author&query=Dovciak%2C+M">Michal Dovciak</a>, <a href="/search/astro-ph?searchtype=author&query=Gnarini%2C+A">Andrea Gnarini</a>, <a href="/search/astro-ph?searchtype=author&query=Iaria%2C+R">Rosario Iaria</a>, <a href="/search/astro-ph?searchtype=author&query=Kajava%2C+J+J+E">Jari J. E. Kajava</a>, <a href="/search/astro-ph?searchtype=author&query=Liu%2C+K">Kuan Liu</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</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=Pilia%2C+M">Maura Pilia</a>, <a href="/search/astro-ph?searchtype=author&query=Rankin%2C+J">John Rankin</a>, <a href="/search/astro-ph?searchtype=author&query=Sanna%2C+A">Andrea Sanna</a>, <a href="/search/astro-ph?searchtype=author&query=Eijnden%2C+J+v+d">Jakob van den Eijnden</a> , et al. (94 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="2306.08476v4-abstract-short" style="display: inline;"> This paper reports the first detection of polarization in the X-rays for atoll-source 4U 1820-303, obtained with the Imaging X-ray Polarimetry Explorer (IXPE) at 99.999% confidence level (CL). Simultaneous polarimetric measurements were also performed in the radio with the Australia Telescope Compact Array (ATCA). The IXPE observations of 4U 1820-303 were coordinated with Swift-XRT, NICER, and NuS… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.08476v4-abstract-full').style.display = 'inline'; document.getElementById('2306.08476v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.08476v4-abstract-full" style="display: none;"> This paper reports the first detection of polarization in the X-rays for atoll-source 4U 1820-303, obtained with the Imaging X-ray Polarimetry Explorer (IXPE) at 99.999% confidence level (CL). Simultaneous polarimetric measurements were also performed in the radio with the Australia Telescope Compact Array (ATCA). The IXPE observations of 4U 1820-303 were coordinated with Swift-XRT, NICER, and NuSTAR aiming to obtain an accurate X-ray spectral model covering a broad energy interval. The source shows a significant polarization above 4 keV, with a polarization degree of 2.0(0.5)% and a polarization angle of -55(7) deg in the 4-7 keV energy range, and a polarization degree of 10(2)% and a polarization angle of -67(7) deg in the 7-8 keV energy bin. This polarization also shows a clear energy trend with polarization degree increasing with energy and a hint for a position-angle change of about 90 deg at 96% CL around 4 keV. The spectro-polarimetric fit indicates that the accretion disk is polarized orthogonally to the hard spectral component, which is presumably produced in the boundary/spreading layer. We do not detect linear polarization from the radio counterpart, with a 99.97% upper limit of 50% at 7.25 GHz. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.08476v4-abstract-full').style.display = 'none'; document.getElementById('2306.08476v4-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJL 953 L22 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.02740">arXiv:2306.02740</a> <span> [<a href="https://arxiv.org/pdf/2306.02740">pdf</a>, <a href="https://arxiv.org/format/2306.02740">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="Solar and Stellar Astrophysics">astro-ph.SR</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/10.1051/0004-6361/202346541">10.1051/0004-6361/202346541 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> X-ray polarimetry and spectroscopy of the neutron star low-mass X-ray binary GX 9+9: an in-depth study with IXPE and NuSTAR </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=Farinelli%2C+R">R. Farinelli</a>, <a href="/search/astro-ph?searchtype=author&query=Gnarini%2C+A">A. Gnarini</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">J. Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">S. Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Capitanio%2C+F">F. Capitanio</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=Fabiani%2C+S">S. Fabiani</a>, <a href="/search/astro-ph?searchtype=author&query=La+Monaca%2C+F">F. La Monaca</a>, <a href="/search/astro-ph?searchtype=author&query=Malacaria%2C+C">C. Malacaria</a>, <a href="/search/astro-ph?searchtype=author&query=Matt%2C+G">G. Matt</a>, <a href="/search/astro-ph?searchtype=author&query=Miku%C5%A1incov%C3%A1%2C+R">R. Miku拧incov谩</a>, <a href="/search/astro-ph?searchtype=author&query=Cocchi%2C+M">M. Cocchi</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">P. Kaaret</a>, <a href="/search/astro-ph?searchtype=author&query=Kajava%2C+J+J+E">J. J. E. Kajava</a>, <a href="/search/astro-ph?searchtype=author&query=Pilia%2C+M">M. Pilia</a>, <a href="/search/astro-ph?searchtype=author&query=Zhang%2C+W">W. Zhang</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+H">W. H. Baumgartner</a>, <a href="/search/astro-ph?searchtype=author&query=Bellazzini%2C+R">R. Bellazzini</a>, <a href="/search/astro-ph?searchtype=author&query=Bongiorno%2C+S+D">S. D. Bongiorno</a>, <a href="/search/astro-ph?searchtype=author&query=Bonino%2C+R">R. Bonino</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="2306.02740v1-abstract-short" style="display: inline;"> We report on a comprehensive analysis of simultaneous X-ray polarimetric and spectral data of the bright atoll source GX 9+9 with the Imaging X-ray Polarimetry Explorer (IXPE) and NuSTAR. The source is significantly polarized in the 4--8 keV band, with a degree of $2.2\% \pm 0.5\%$ (uncertainty at the 68% confidence level). The NuSTAR broad-band spectrum clearly shows an iron line, and is well des… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.02740v1-abstract-full').style.display = 'inline'; document.getElementById('2306.02740v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.02740v1-abstract-full" style="display: none;"> We report on a comprehensive analysis of simultaneous X-ray polarimetric and spectral data of the bright atoll source GX 9+9 with the Imaging X-ray Polarimetry Explorer (IXPE) and NuSTAR. The source is significantly polarized in the 4--8 keV band, with a degree of $2.2\% \pm 0.5\%$ (uncertainty at the 68% confidence level). The NuSTAR broad-band spectrum clearly shows an iron line, and is well described by a model including thermal disk emission, a Comptonized component, and reflection. From a spectro-polarimetric fit, we obtain an upper limit to the polarization degree of the disk of 4% (at 99% confidence level), while the contribution of Comptonized and reflected radiation cannot be conclusively separated. However, the polarization is consistent with resulting from a combination of Comptonization in a boundary or spreading layer, plus reflection off the disc, which gives a significant contribution in any realistic scenario. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.02740v1-abstract-full').style.display = 'none'; document.getElementById('2306.02740v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 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">10 pages, 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 676, A20 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.02116">arXiv:2306.02116</a> <span> [<a href="https://arxiv.org/pdf/2306.02116">pdf</a>, <a href="https://arxiv.org/format/2306.02116">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/10.1051/0004-6361/202347088">10.1051/0004-6361/202347088 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Complex variations of X-ray polarization in the X-ray pulsar LS V +44 17/RX J0440.9+4431 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">Victor Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Heyl%2C+J">Jeremy Heyl</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=Caiazzo%2C+I">Ilaria Caiazzo</a>, <a href="/search/astro-ph?searchtype=author&query=Turolla%2C+R">Roberto Turolla</a>, <a href="/search/astro-ph?searchtype=author&query=Veledina%2C+A">Alexandra Veledina</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=Forsblom%2C+S+V">Sofia V. Forsblom</a>, <a href="/search/astro-ph?searchtype=author&query=Gonz%C3%A1lez-Caniulef%2C+D">Denis Gonz谩lez-Caniulef</a>, <a href="/search/astro-ph?searchtype=author&query=Loktev%2C+V">Vladislav Loktev</a>, <a href="/search/astro-ph?searchtype=author&query=Malacaria%2C+C">Christian Malacaria</a>, <a href="/search/astro-ph?searchtype=author&query=Mushtukov%2C+A+A">Alexander A. Mushtukov</a>, <a href="/search/astro-ph?searchtype=author&query=Suleimanov%2C+V+F">Valery F. Suleimanov</a>, <a href="/search/astro-ph?searchtype=author&query=Lutovinov%2C+A+A">Alexander A. Lutovinov</a>, <a href="/search/astro-ph?searchtype=author&query=Mereminskiy%2C+I+A">Ilya A. Mereminskiy</a>, <a href="/search/astro-ph?searchtype=author&query=Molkov%2C+S+V">Sergey V. Molkov</a>, <a href="/search/astro-ph?searchtype=author&query=Salganik%2C+A">Alexander Salganik</a>, <a href="/search/astro-ph?searchtype=author&query=Santangelo%2C+A">Andrea Santangelo</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=Kravtsov%2C+V">Vadim Kravtsov</a>, <a href="/search/astro-ph?searchtype=author&query=Nitindala%2C+A+P">Anagha P. Nitindala</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>, <a href="/search/astro-ph?searchtype=author&query=Bachetti%2C+M">Matteo Bachetti</a> , et al. (87 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="2306.02116v2-abstract-short" style="display: inline;"> We report on Imaging X-ray polarimetry explorer (IXPE) observations of the Be-transient X-ray pulsar LS V +44 17/RX J0440.9+4431 made at two luminosity levels during the giant outburst in January--February 2023. Considering the observed spectral variability and changes in the pulse profiles, the source was likely caught in supercritical and subcritical states with significantly different emission-… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.02116v2-abstract-full').style.display = 'inline'; document.getElementById('2306.02116v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.02116v2-abstract-full" style="display: none;"> We report on Imaging X-ray polarimetry explorer (IXPE) observations of the Be-transient X-ray pulsar LS V +44 17/RX J0440.9+4431 made at two luminosity levels during the giant outburst in January--February 2023. Considering the observed spectral variability and changes in the pulse profiles, the source was likely caught in supercritical and subcritical states with significantly different emission-region geometry, associated with the presence of accretion columns and hot spots, respectively. We focus here on the pulse-phase-resolved polarimetric analysis and find that the observed dependencies of the polarization degree and polarization angle (PA) on the pulse phase are indeed drastically different for the two observations. The observed differences, if interpreted within the framework of the rotating vector model (RVM), imply dramatic variations in the spin axis inclination, the position angle, and the magnetic colatitude by tens of degrees within the space of just a few days. We suggest that the apparent changes in the observed PA phase dependence are predominantly related to the presence of an unpulsed polarized component in addition to the polarized radiation associated with the pulsar itself. We then show that the observed PA phase dependence in both observations can be explained with a single set of RVM parameters defining the pulsar's geometry. We also suggest that the additional polarized component is likely produced by scattering of the pulsar radiation in the equatorial disk wind. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.02116v2-abstract-full').style.display = 'none'; document.getElementById('2306.02116v2-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 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 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">10 pages, 7 figures, accepted in A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 677, A57 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.15309">arXiv:2305.15309</a> <span> [<a href="https://arxiv.org/pdf/2305.15309">pdf</a>, <a href="https://arxiv.org/format/2305.15309">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> <div 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/10.1051/0004-6361/202346994">10.1051/0004-6361/202346994 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> X-ray polarimetry of the accreting pulsar GX 301-2 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Suleimanov%2C+V+F">Valery F. Suleimanov</a>, <a href="/search/astro-ph?searchtype=author&query=Forsblom%2C+S+V">Sofia V. Forsblom</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=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+V">Victor Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Doroshenko%2C+R">Rosalia Doroshenko</a>, <a href="/search/astro-ph?searchtype=author&query=Capitanio%2C+F">Fiamma Capitanio</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=Gonz%C3%A1lez-Caniulef%2C+D">Denis Gonz谩lez-Caniulef</a>, <a href="/search/astro-ph?searchtype=author&query=Heyl%2C+J">Jeremy Heyl</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=Lutovinov%2C+A+A">Alexander A. Lutovinov</a>, <a href="/search/astro-ph?searchtype=author&query=Molkov%2C+S+V">Sergey V. Molkov</a>, <a href="/search/astro-ph?searchtype=author&query=Malacaria%2C+C">Christian Malacaria</a>, <a href="/search/astro-ph?searchtype=author&query=Mushtukov%2C+A+A">Alexander A. Mushtukov</a>, <a href="/search/astro-ph?searchtype=author&query=Shtykovsky%2C+A+E">Andrey E. Shtykovsky</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>, <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. (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="2305.15309v2-abstract-short" style="display: inline;"> The phase- and energy-resolved polarization measurements of accreting X-ray pulsars (XRPs) allow us to test different theoretical models of their emission, and they also provide an avenue to determine the emission region geometry. We present the results of the observations of the XRP GX 301-2 performed with the Imaging X-ray Polarimetry Explorer (IXPE). A persistent XRP, GX 301-2 has one of the lo… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.15309v2-abstract-full').style.display = 'inline'; document.getElementById('2305.15309v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.15309v2-abstract-full" style="display: none;"> The phase- and energy-resolved polarization measurements of accreting X-ray pulsars (XRPs) allow us to test different theoretical models of their emission, and they also provide an avenue to determine the emission region geometry. We present the results of the observations of the XRP GX 301-2 performed with the Imaging X-ray Polarimetry Explorer (IXPE). A persistent XRP, GX 301-2 has one of the longest spin periods known: $\sim$680s. A massive hyper-giant companion star Wray 977 supplies mass to the neutron star via powerful stellar winds. We did not detect significant polarization in the phase-averaged data when using spectro-polarimetric analysis, with the upper limit on the polarization degree (PD) of 2.3% (99% confidence level). Using the phase-resolved spectro-polarimetric analysis, we obtained a significant detection of polarization (above 99% confidence level) in two out of nine phase bins and a marginal detection in three bins, with a PD ranging between $\sim$3% and $\sim$10% and a polarization angle varying in a very wide range from $\sim$0 degree to $\sim$160 degree. Using the rotating vector model, we obtained constraints on the pulsar geometry using both phase-binned and unbinned analyses, finding excellent agreement. Finally, we discuss possible reasons for a low observed polarization in GX 301-2. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.15309v2-abstract-full').style.display = 'none'; document.getElementById('2305.15309v2-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">v1</span> submitted 24 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">10 pages, 10 figures, accepted for publication in A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 678, A119 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.13898">arXiv:2305.13898</a> <span> [<a href="https://arxiv.org/pdf/2305.13898">pdf</a>, <a href="https://arxiv.org/format/2305.13898">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Astrophysics of Galaxies">astro-ph.GA</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/2041-8213/acd242">10.3847/2041-8213/acd242 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> X-ray Polarization of BL Lacertae in Outburst </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Peirson%2C+A+L">Abel L. Peirson</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Pacciani%2C+L">Luigi Pacciani</a>, <a href="/search/astro-ph?searchtype=author&query=Romani%2C+R+W">Roger W. Romani</a>, <a href="/search/astro-ph?searchtype=author&query=Wu%2C+K">Kinwah Wu</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Lalla%2C+N">Niccolo Di Lalla</a>, <a href="/search/astro-ph?searchtype=author&query=Omodei%2C+N">Nicola Omodei</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Ivan Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Kouch%2C+P+M">Pouya M. Kouch</a>, <a href="/search/astro-ph?searchtype=author&query=Lindfors%2C+E">Elina Lindfors</a>, <a href="/search/astro-ph?searchtype=author&query=Aceituno%2C+F+J">Francisco Jose Aceituno</a>, <a href="/search/astro-ph?searchtype=author&query=Bernardos%2C+M+I">Maria I. Bernardos</a>, <a href="/search/astro-ph?searchtype=author&query=Bonnoli%2C+G">Giacomo Bonnoli</a>, <a href="/search/astro-ph?searchtype=author&query=Casanova%2C+V">Victor Casanova</a>, <a href="/search/astro-ph?searchtype=author&query=Garcia-Comas%2C+M">Maya Garcia-Comas</a>, <a href="/search/astro-ph?searchtype=author&query=Agis-Gonzalez%2C+B">Beatriz Agis-Gonzalez</a>, <a href="/search/astro-ph?searchtype=author&query=Husillos%2C+C">Cesar Husillos</a>, <a href="/search/astro-ph?searchtype=author&query=Marchini%2C+A">Alessandro Marchini</a> , et al. (106 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.13898v2-abstract-short" style="display: inline;"> We report the first $> 99\%$ confidence detection of X-ray polarization in BL Lacertae. During a recent X-ray/$纬$-ray outburst, a 287 ksec observation (2022 November 27-30) was taken using the Imaging X-ray Polarimetry Explorer ({\it IXPE}), together with contemporaneous multiwavelength observations from the Neil Gehrels {\it Swift} observatory and {\it XMM-Newton} in soft X-rays (0.3--10~keV), {\… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.13898v2-abstract-full').style.display = 'inline'; document.getElementById('2305.13898v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.13898v2-abstract-full" style="display: none;"> We report the first $> 99\%$ confidence detection of X-ray polarization in BL Lacertae. During a recent X-ray/$纬$-ray outburst, a 287 ksec observation (2022 November 27-30) was taken using the Imaging X-ray Polarimetry Explorer ({\it IXPE}), together with contemporaneous multiwavelength observations from the Neil Gehrels {\it Swift} observatory and {\it XMM-Newton} in soft X-rays (0.3--10~keV), {\it NuSTAR} in hard X-rays (3--70~keV), and optical polarization from the Calar Alto, and Perkins Telescope observatories. Our contemporaneous X-ray data suggest that the {\it IXPE} energy band is at the crossover between the low- and high-frequency blazar emission humps. The source displays significant variability during the observation, and we measure polarization in three separate time bins. Contemporaneous X-ray spectra allow us to determine the relative contribution from each emission hump. We find $>99\%$ confidence X-ray polarization $螤_{2-4{\rm keV}} = 21.7^{+5.6}_{-7.9}\%$ and electric vector polarization angle $蠄_{2-4{\rm keV}} = -28.7 \pm 8.7^{\circ}$ in the time bin with highest estimated synchrotron flux contribution. We discuss possible implications of our observations, including previous {\it IXPE} BL Lacertae pointings, tentatively concluding that synchrotron self-Compton emission dominates over hadronic emission processes during the observed epochs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.13898v2-abstract-full').style.display = 'none'; document.getElementById('2305.13898v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted to ApJL. 16 pages, 8 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2305.13497">arXiv:2305.13497</a> <span> [<a href="https://arxiv.org/pdf/2305.13497">pdf</a>, <a href="https://arxiv.org/format/2305.13497">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="High Energy Astrophysical Phenomena">astro-ph.HE</span> </div> </div> <p class="title is-5 mathjax"> Discovery of X-ray polarization angle rotation in active galaxy Mrk 421 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Di+Gesu%2C+L">Laura Di Gesu</a>, <a href="/search/astro-ph?searchtype=author&query=Marshall%2C+H+L">Herman L. Marshall</a>, <a href="/search/astro-ph?searchtype=author&query=Ehlert%2C+S+R">Steven R. Ehlert</a>, <a href="/search/astro-ph?searchtype=author&query=Kim%2C+D+E">Dawoon E. Kim</a>, <a href="/search/astro-ph?searchtype=author&query=Donnarumma%2C+I">Immacolata Donnarumma</a>, <a href="/search/astro-ph?searchtype=author&query=Tavecchio%2C+F">Fabrizio Tavecchio</a>, <a href="/search/astro-ph?searchtype=author&query=Liodakis%2C+I">Ioannis Liodakis</a>, <a href="/search/astro-ph?searchtype=author&query=Kiehlmann%2C+S">Sebastian Kiehlmann</a>, <a href="/search/astro-ph?searchtype=author&query=Agudo%2C+I">Iv谩n Agudo</a>, <a href="/search/astro-ph?searchtype=author&query=Jorstad%2C+S+G">Svetlana G. Jorstad</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Marscher%2C+A+P">Alan P. Marscher</a>, <a href="/search/astro-ph?searchtype=author&query=Puccetti%2C+S">Simonetta Puccetti</a>, <a href="/search/astro-ph?searchtype=author&query=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Perri%2C+M">Matteo Perri</a>, <a href="/search/astro-ph?searchtype=author&query=Pacciani%2C+L">Luigi Pacciani</a>, <a href="/search/astro-ph?searchtype=author&query=Negro%2C+M">Michela Negro</a>, <a href="/search/astro-ph?searchtype=author&query=Romani%2C+R+W">Roger W. Romani</a>, <a href="/search/astro-ph?searchtype=author&query=Di+Marco%2C+A">Alessandro Di Marco</a>, <a href="/search/astro-ph?searchtype=author&query=Blinov%2C+D">Dmitry Blinov</a>, <a href="/search/astro-ph?searchtype=author&query=Bourbah%2C+I+G">Ioakeim G. Bourbah</a>, <a href="/search/astro-ph?searchtype=author&query=Kontopodis%2C+E">Evangelos Kontopodis</a>, <a href="/search/astro-ph?searchtype=author&query=Mandarakas%2C+N">Nikos Mandarakas</a>, <a href="/search/astro-ph?searchtype=author&query=Romanopoulos%2C+S">Stylianos Romanopoulos</a>, <a href="/search/astro-ph?searchtype=author&query=Skalidis%2C+R">Raphael Skalidis</a> , et al. (118 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2305.13497v1-abstract-short" style="display: inline;"> The magnetic field conditions in astrophysical relativistic jets can be probed by multiwavelength polarimetry, which has been recently extended to X-rays. For example, one can track how the magnetic field changes in the flow of the radiating particles by observing rotations of the electric vector position angle $唯$. Here we report the discovery of a $唯_{\mathrm x}$ rotation in the X-ray band in th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.13497v1-abstract-full').style.display = 'inline'; document.getElementById('2305.13497v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.13497v1-abstract-full" style="display: none;"> The magnetic field conditions in astrophysical relativistic jets can be probed by multiwavelength polarimetry, which has been recently extended to X-rays. For example, one can track how the magnetic field changes in the flow of the radiating particles by observing rotations of the electric vector position angle $唯$. Here we report the discovery of a $唯_{\mathrm x}$ rotation in the X-ray band in the blazar Mrk 421 at an average flux state. Across the 5 days of Imaging X-ray Polarimetry Explorer (IXPE) observations of 4-6 and 7-9 June 2022, $唯_{\mathrm x}$ rotated in total by $\geq360^\circ$. Over the two respective date ranges, we find constant, within uncertainties, rotation rates ($80 \pm 9$ and $91 \pm 8 ^\circ/\rm day$) and polarization degrees ($螤_{\mathrm x}=10\%\pm1\%$). Simulations of a random walk of the polarization vector indicate that it is unlikely that such rotation(s) are produced by a stochastic process. The X-ray emitting site does not completely overlap the radio/infrared/optical emission sites, as no similar rotation of $唯$ was observed in quasi-simultaneous data at longer wavelengths. We propose that the observed rotation was caused by a helical magnetic structure in the jet, illuminated in the X-rays by a localized shock propagating along this helix. The optically emitting region likely lies in a sheath surrounding an inner spine where the X-ray radiation is released. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.13497v1-abstract-full').style.display = 'none'; document.getElementById('2305.13497v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/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/2305.10630">arXiv:2305.10630</a> <span> [<a href="https://arxiv.org/pdf/2305.10630">pdf</a>, <a href="https://arxiv.org/format/2305.10630">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 First X-ray Polarization Observation of the Black Hole X-ray Binary 4U 1630-47 in the Steep Power Law State </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/astro-ph?searchtype=author&query=Cavero%2C+N+R">Nicole Rodriguez Cavero</a>, <a href="/search/astro-ph?searchtype=author&query=Marra%2C+L">Lorenzo Marra</a>, <a href="/search/astro-ph?searchtype=author&query=Krawczynski%2C+H">Henric Krawczynski</a>, <a href="/search/astro-ph?searchtype=author&query=Dov%C4%8Diak%2C+M">Michal Dov膷iak</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">Stefano Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Steiner%2C+J+F">James F. Steiner</a>, <a href="/search/astro-ph?searchtype=author&query=Svoboda%2C+J">Jiri Svoboda</a>, <a href="/search/astro-ph?searchtype=author&query=Capitanio%2C+F">Fiamma Capitanio</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=Ingram%2C+A">Adam Ingram</a>, <a href="/search/astro-ph?searchtype=author&query=Veledina%2C+A">Alexandra Veledina</a>, <a href="/search/astro-ph?searchtype=author&query=Taverna%2C+R">Roberto Taverna</a>, <a href="/search/astro-ph?searchtype=author&query=Karas%2C+V">Vladimir Karas</a>, <a href="/search/astro-ph?searchtype=author&query=Ursini%2C+F">Francesco Ursini</a>, <a href="/search/astro-ph?searchtype=author&query=Podgorn%C3%BD%2C+J">Jakub Podgorn媒</a>, <a href="/search/astro-ph?searchtype=author&query=Ratheesh%2C+A">Ajay Ratheesh</a>, <a href="/search/astro-ph?searchtype=author&query=Suleimanov%2C+V">Valery Suleimanov</a>, <a href="/search/astro-ph?searchtype=author&query=Miku%C5%A1incov%C3%A1%2C+R">Romana Miku拧incov谩</a>, <a href="/search/astro-ph?searchtype=author&query=Zane%2C+S">Silvia Zane</a>, <a href="/search/astro-ph?searchtype=author&query=Kaaret%2C+P">Philip Kaaret</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Poutanen%2C+J">Juri Poutanen</a>, <a href="/search/astro-ph?searchtype=author&query=Malacaria%2C+C">Christian Malacaria</a>, <a href="/search/astro-ph?searchtype=author&query=Petrucci%2C+P">Pierre-Olivier Petrucci</a> , et al. (85 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="2305.10630v1-abstract-short" style="display: inline;"> The Imaging X-ray Polarimetry Explorer (IXPE) observed the black hole X-ray binary 4U 1630-47 in the steep power law (or very high) state. The observations reveal a linear polarization degree of the 2-8 keV X-rays of 6.8 +/- 0.2 % at a position angle of 21掳.3 +/- 0掳.9 East of North (all errors at 1蟽 confidence level). Whereas the polarization degree increases with energy, the polarization angle st… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.10630v1-abstract-full').style.display = 'inline'; document.getElementById('2305.10630v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.10630v1-abstract-full" style="display: none;"> The Imaging X-ray Polarimetry Explorer (IXPE) observed the black hole X-ray binary 4U 1630-47 in the steep power law (or very high) state. The observations reveal a linear polarization degree of the 2-8 keV X-rays of 6.8 +/- 0.2 % at a position angle of 21掳.3 +/- 0掳.9 East of North (all errors at 1蟽 confidence level). Whereas the polarization degree increases with energy, the polarization angle stays constant within the accuracy of our measurements. We compare the polarization of the source in the steep power-law state with the previous IXPE measurement of the source in the high soft state. We find that even though the source flux and spectral shape are significantly different between the high soft state and the steep power-law state, their polarization signatures are similar. Assuming that the polarization of both the thermal and power-law emission components are constant over time, we estimate the power-law component polarization to be 6.8-7.0% and note that the polarization angle of the thermal and power-law components must be approximately aligned. We discuss the implications for the origin of the power-law component and the properties of the emitting plasma. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.10630v1-abstract-full').style.display = 'none'; document.getElementById('2305.10630v1-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">14 pages, 2 tables, 6 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/2304.06967">arXiv:2304.06967</a> <span> [<a href="https://arxiv.org/pdf/2304.06967">pdf</a>, <a href="https://arxiv.org/format/2304.06967">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/10.1038/s41586-023-06064-x">10.1038/s41586-023-06064-x <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> X-ray polarization evidence for a 200 years-old flare of Sgr A$^*$ </p> <p class="authors"> <span class="search-hit">Authors:</span> <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=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=Ferrazzoli%2C+R">Riccardo Ferrazzoli</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=Barnouin%2C+T">Thibault Barnouin</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=Middei%2C+R">Riccardo Middei</a>, <a href="/search/astro-ph?searchtype=author&query=Vikhlinin%2C+A">Alexey Vikhlinin</a>, <a href="/search/astro-ph?searchtype=author&query=Costa%2C+E">Enrico Costa</a>, <a href="/search/astro-ph?searchtype=author&query=Soffitta%2C+P">Paolo Soffitta</a>, <a href="/search/astro-ph?searchtype=author&query=Muleri%2C+F">Fabio Muleri</a>, <a href="/search/astro-ph?searchtype=author&query=Sunyaev%2C+R">Rashid Sunyaev</a>, <a href="/search/astro-ph?searchtype=author&query=Forman%2C+W">William Forman</a>, <a href="/search/astro-ph?searchtype=author&query=Kraft%2C+R">Ralph Kraft</a>, <a href="/search/astro-ph?searchtype=author&query=Bianchi%2C+S">Stefano Bianchi</a>, <a href="/search/astro-ph?searchtype=author&query=Donnarumma%2C+I">Immacolata Donnarumma</a>, <a href="/search/astro-ph?searchtype=author&query=Petrucci%2C+P">Pierre-Olivier Petrucci</a>, <a href="/search/astro-ph?searchtype=author&query=Enoto%2C+T">Teruaki Enoto</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>, <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> , 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="2304.06967v1-abstract-short" style="display: inline;"> The center of the Milky Way Galaxy hosts a $\sim$4 million solar mass black hole (Sgr A$^*$) that is currently very quiescent with a luminosity many orders of magnitude below those of active galactic nuclei. Reflection of X-rays from Sgr A$^*$ by dense gas in the Galactic Center region offers a means to study its past flaring activity on times scales of hundreds and thousands of years. The shape o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.06967v1-abstract-full').style.display = 'inline'; document.getElementById('2304.06967v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.06967v1-abstract-full" style="display: none;"> The center of the Milky Way Galaxy hosts a $\sim$4 million solar mass black hole (Sgr A$^*$) that is currently very quiescent with a luminosity many orders of magnitude below those of active galactic nuclei. Reflection of X-rays from Sgr A$^*$ by dense gas in the Galactic Center region offers a means to study its past flaring activity on times scales of hundreds and thousands of years. The shape of the X-ray continuum and the strong fluorescent iron line observed from giant molecular clouds in the vicinity of Sgr A$^*$ are consistent with the reflection scenario. If this interpretation is correct, the reflected continuum emission should be polarized. Here we report observations of polarized X-ray emission in the direction of the Galactic center molecular clouds using the Imaging X-ray Polarimetry Explorer (IXPE). We measure a polarization degree of 31\% $\pm$ 11\%, and a polarization angle of $-$48$^\circ$ $\pm$ 11$^\circ$. The polarization angle is consistent with Sgr A$^*$ being the primary source of the emission, while the polarization degree implies that some 200 years ago the X-ray luminosity of Sgr A$^*$ was briefly comparable to a Seyfert galaxy. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.06967v1-abstract-full').style.display = 'none'; document.getElementById('2304.06967v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">24 pages, 5 figures, 4 tables, author's version of the paper accepted for publication in Nature</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> </li> </ol> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Marshall%2C+H+L&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Marshall%2C+H+L&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Marshall%2C+H+L&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> <li> <a href="/search/?searchtype=author&query=Marshall%2C+H+L&start=100" class="pagination-link " aria-label="Page 3" aria-current="page">3 </a> </li> <li> <a 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