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

DOI: 
10.3847/2041-8213/acb703
Publication date: 
15/02/2023
Main author: 
Zane, Silvia
IAA authors: 
Agudo, Iván
Authors: 
Zane, Silvia;Taverna, Roberto;González-Caniulef, Denis;Muleri, Fabio;Turolla, Roberto;Heyl, Jeremy;Uchiyama, Keisuke;Ng, Mason;Tamagawa, Toru;Caiazzo, Ilaria;Di Lalla, Niccolò;Marshall, Herman L.;Bachetti, Matteo;La Monaca, Fabio;Gau, Ephraim;Di Marco, Alessandro;Baldini, Luca;Negro, Michela;Omodei, Nicola;Rankin, John;Matt, Giorgio;Pavlov, George G.;Kitaguchi, Takao;Krawczynski, Henric;Kislat, Fabian;Kelly, Ruth;Agudo, Iván;Antonelli, Lucio A.;Baumgartner, Wayne H.;Bellazzini, Ronaldo;Bianchi, Stefano;Bongiorno, Stephen D.;Bonino, Raffaella;Brez, Alessandro;Bucciantini, Niccolò;Capitanio, Fiamma;Castellano, Simone;Cavazzuti, Elisabetta;Chen, Chieng-Ting;Ciprini, Stefano;Costa, Enrico;De Rosa, Alessandra;Del Monte, Ettore;Di Gesu, Laura;Donnarumma, Immacolata;Doroshenko, Victor;Dovčiak, Michal;Ehlert, Steven R.;Enoto, Teruaki;Evangelista, Yuri;Fabiani, Sergio;Ferrazzoli, Riccardo;Garcia, Javier A.;Gunji, Shuichi;Hayashida, Kiyoshi;Iwakiri, Wataru;Jorstad, Svetlana G.;Kaaret, Philip;Karas, Vladimir;Kolodziejczak, Jeffery J.;Latronico, Luca;Liodakis, Ioannis;Maldera, Simone;Manfreda, Alberto;Marin, Frédéric;Marinucci, Andrea;Marscher, Alan P.;Massaro, Francesco;Mitsuishi, Ikuyuki;Mizuno, Tsunefumi;Ng, C. -Y.;O'Dell, Stephen L.;Oppedisano, Chiara;Papitto, Alessandro;Peirson, Abel L.;Perri, Matteo;Pesce-Rollins, Melissa;Petrucci, Pierre-Olivier;Pilia, Maura;Possenti, Andrea;Poutanen, Juri;Puccetti, Simonetta;Ramsey, Brian D.;Ratheesh, Ajay;Roberts, Oliver J.;Romani, Roger W.;Sgró, Carmelo;Slane, Patrick;Soffitta, Paolo;Spandre, Gloria;Swartz, Douglas A.;Tavecchio, Fabrizio;Tawara, Yuzuru;Tennant, Allyn F.;Thomas, Nicholas E.;Tombesi, Francesco;Trois, Alessio;Tsygankov, Sergey S.;Vink, Jacco;Weisskopf, Martin C.;Wu, Kinwah;Xie, Fei
Journal: 
Astrophysical Journal Letters
Publication type: 
Article
Volume: 
944
Pages: 
L27
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.
Database: 
ADS
SCOPUS
URL: 
https://ui.adsabs.harvard.edu/#abs/2023ApJ...944L..27Z/abstract
ADS Bibcode: 
2023ApJ...944L..27Z
Keywords: 
Polarimetry;Magnetars;1278;992;Astrophysics - High Energy Astrophysical Phenomena