A Strong X-Ray Polarization Signal from the Magnetar 1RXS J170849.0-400910

Zane, Silvia and Taverna, Roberto and González–Caniulef, Denis and Muleri, Fabio and Turolla, Roberto and Heyl, Jeremy and Uchiyama, Keisuke and Ng, Mason and Tamagawa, Toru and Caiazzo, Ilaria and Di Lalla, Niccolò and Marshall, Herman L. and Bachetti, Matteo and La Monaca, Fabio and Gau, Ephraim and Di Marco, Alessandro and Baldini, Luca and Negro, Michela and Omodei, Nicola and Rankin, John and Matt, Giorgio and Pavlov, George G. and Kitaguchi, Takao and Krawczynski, Henric and Kislat, Fabian and Kelly, Ruth and Agudo, Iván and Antonelli, Lucio A. and Baumgartner, Wayne H. and Bellazzini, Ronaldo and Bianchi, Stefano and Bongiorno, Stephen D. and Bonino, Raffaella and Brez, Alessandro and Bucciantini, Niccolò and Capitanio, Fiamma and Castellano, Simone and Cavazzuti, Elisabetta and Chen, Chieng-Ting and Ciprini, Stefano and Costa, Enrico and De Rosa, Alessandra and Del Monte, Ettore and Di Gesu, Laura and Donnarumma, Immacolata and Doroshenko, Victor and Dovčiak, Michal and Ehlert, Steven R. and Enoto, Teruaki and Evangelista, Yuri and Fabiani, Sergio and Ferrazzoli, Riccardo and Garcia, Javier A. and Gunji, Shuichi and Hayashida, Kiyoshi and Iwakiri, Wataru and Jorstad, Svetlana G. and Kaaret, Philip and Karas, Vladimir and Kolodziejczak, Jeffery J. and Latronico, Luca and Liodakis, Ioannis and Maldera, Simone and Manfreda, Alberto and Marin, Frédéric and Marinucci, Andrea and Marscher, Alan P. and Massaro, Francesco and Mitsuishi, Ikuyuki and Mizuno, Tsunefumi and Ng, C.-Y. and O’Dell, Stephen L. and Oppedisano, Chiara and Papitto, Alessandro and Peirson, Abel L. and Perri, Matteo and Pesce-Rollins, Melissa and Petrucci, Pierre-Olivier and Pilia, Maura and Possenti, Andrea and Poutanen, Juri and Puccetti, Simonetta and Ramsey, Brian D. and Ratheesh, Ajay and Roberts, Oliver J. and Romani, Roger W. and Sgró, Carmelo and Slane, Patrick and Soffitta, Paolo and Spandre, Gloria and Swartz, Douglas A. and Tavecchio, Fabrizio and Tawara, Yuzuru and Tennant, Allyn F. and Thomas, Nicholas E. and Tombesi, Francesco and Trois, Alessio and Tsygankov, Sergey S. and Vink, Jacco and Weisskopf, Martin C. and Wu, Kinwah and Xie, Fei (2023) A Strong X-Ray Polarization Signal from the Magnetar 1RXS J170849.0-400910. The Astrophysical Journal Letters, 944 (2). L27. ISSN 2041-8205

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Abstract

Magnetars are the most strongly magnetized neutron stars, and one of the most promising targets for X-ray polarimetric measurements. We present here the first Imaging X-ray Polarimetry Explorer observation of the magnetar 1RXS J170849.0-400910, jointly analyzed with a new Swift observation and archival NICER data. The total (energy- and phase-integrated) emission in the 2–8 keV energy range is linerarly polarized, at a ∼35% level. The phase-averaged polarization signal shows a marked increase with energy, ranging from ∼20% at 2–3 keV up to ∼80% at 6–8 keV, while the polarization angle remains constant. This indicates that radiation is mostly polarized in a single direction. The spectrum is well reproduced by a combination of either two thermal (blackbody) components or a blackbody and a power law. Both the polarization degree and angle also show a variation with the spin phase, and the former is almost anticorrelated with the source counts in the 2–8 and 2–4 keV bands. We discuss the possible implications and interpretations, based on a joint analysis of the spectral, polarization, and pulsation properties of the source. A scenario in which the surface temperature is not homogeneous, with a hotter cap covered by a gaseous atmosphere and a warmer region in a condensed state, provides a satisfactory description of both the phase- and energy-dependent spectro-polarimetric data. The (comparatively) small size of the two emitting regions, required to explain the observed pulsations, does not allow to reach a robust conclusion about the presence of vacuum birefringence effects.

Item Type: Article
Subjects: Digital Academic Press > Physics and Astronomy
Depositing User: Unnamed user with email support@digiacademicpress.org
Date Deposited: 18 Apr 2023 05:52
Last Modified: 02 Oct 2024 06:55
URI: http://science.researchersasian.com/id/eprint/936

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