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arXiv · 2305.15309

X-ray polarimetry of the accreting pulsar GX 301-2

Valery F. Suleimanov·Sofia V. Forsblom·Sergey S. Tsygankov·Juri Poutanen·Victor Doroshenko·Rosalia Doroshenko·Fiamma Capitanio·Alessandro Di Marco·Denis González-Caniulef·Jeremy Heyl·Fabio La Monaca·Alexander A. Lutovinov·Sergey V. Molkov·Christian Malacaria·Alexander A. Mushtukov·Andrey E. Shtykovsky·Iván Agudo·Lucio A. Antonelli·Matteo Bachetti·Luca Baldini·Wayne H. Baumgartner·Ronaldo Bellazzini·Stefano Bianchi·Stephen D. Bongiorno·Raffaella Bonino·Alessandro Brez·Niccolò Bucciantini·Simone Castellano·Elisabetta Cavazzuti·Chien-Ting Chen·Stefano Ciprini·Enrico Costa·Alessandra De Rosa·Ettore Del Monte·Laura Di Gesu·Niccolò Di Lalla·Immacolata Donnarumma·Michal Dovčiak·Steven R. Ehlert·Teruaki Enoto·Yuri Evangelista·Sergio Fabiani·Riccardo Ferrazzoli·Javier A. Garcia·Shuichi Gunji·Kiyoshi Hayashida·Wataru Iwakiri·Svetlana G. Jorstad·Philip Kaaret·Vladimir Karas·Fabian Kislat·Takao Kitaguchi·Jeffery J. Kolodziejczak·Henric Krawczynski·Luca Latronico·Ioannis Liodakis·Simone Maldera·Alberto Manfreda·Frédéric Marin·Andrea Marinucci·Alan P. Marscher·Herman L. Marshall·Francesco Massaro·Giorgio Matt·Ikuyuki Mitsuishi·Tsunefumi Mizuno·Fabio Muleri·Michela Negro·Chi-Yung Ng·Stephen L. O'Dell·Nicola Omodei·Chiara Oppedisano·Alessandro Papitto·George G. Pavlov·Abel L. Peirson·Matteo Perri·Melissa Pesce Rollins·Pierre Olivier Petrucci·Maura Pilia·Andrea Possenti·Simonetta Puccetti·Brian D. Ramsey·John Rankin·Ajay Ratheesh·Oliver J. Roberts·Roger W. Romani·Carmelo Sgrò·Patrick Slane·Paolo Soffitta·Gloria Spandre·Douglas A. Swartz·Toru Tamagawa·Fabrizio Tavecchio·Roberto Taverna·Yuzuru Tawara·Allyn F. Tennant·Nicholas E. Thomas·Francesco Tombesi·Alessio Trois·Roberto Turolla

Abstract

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.

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Valery F. Suleimanov, Sofia V. Forsblom, Sergey S. Tsygankov, Juri Poutanen, Victor Doroshenko, Rosalia Doroshenko, Fiamma Capitanio, Alessandro Di Marco, Denis González-Caniulef, Jeremy Heyl, Fabio La Monaca, Alexander A. Lutovinov, Sergey V. Molkov, Christian Malacaria, Alexander A. Mushtukov, Andrey E. Shtykovsky, Iván Agudo, Lucio A. Antonelli, Matteo Bachetti, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Enrico Costa, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccolò Di Lalla, Immacolata Donnarumma, Michal Dovčiak, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Wataru Iwakiri, Svetlana G. Jorstad, Philip Kaaret, Vladimir Karas, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Alan P. Marscher, Herman L. Marshall, Francesco Massaro, Giorgio Matt, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Fabio Muleri, Michela Negro, Chi-Yung Ng, Stephen L. O'Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Matteo Perri, Melissa Pesce Rollins, Pierre Olivier Petrucci, Maura Pilia, Andrea Possenti, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Ajay Ratheesh, Oliver J. Roberts, Roger W. Romani, Carmelo Sgrò, Patrick Slane, Paolo Soffitta, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Roberto Turolla. 2023-09-04. X-ray polarimetry of the accreting pulsar GX 301-2. https://doi.org/10.1051/0004-6361%2F202346994

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