Title: | Highly Significant Detection of X-Ray Polarization from the Brightest Accreting Neutron Star Sco X-1 |
Authors: | LA MONACA, Fabio DI MARCO, Alessandro Poutanen, Juri BACHETTI, Matteo MOTTA, Sara Elisa PAPITTO, ALESSANDRO PILIA, Maura XIE, FEI Bianchi, Stefano Bobrikova, Anna COSTA, ENRICO RATHEESH, AJAY Roberts, Oliver J. Romani, Roger W. Sgrò, Carmelo Slane, Patrick Spandre, Gloria Swartz, Douglas A. Tamagawa, Toru TAVECCHIO, Fabrizio Taverna, Roberto Deng, Wei Tawara, Yuzuru Tennant, Allyn F. Thomas, Nicholas E. TOMBESI, Francesco TROIS, ALESSIO Tsygankov, Sergey S. Turolla, Roberto Vink, Jacco Wu, Kinwah IXPE Collaboration Ge, Ming-Yu ILLIANO, Giulia Jia, Shu-Mei Krawczynski, Henric LAI, Eleonora Veronica Liu, Kuan MASTROSERIO, Guglielmo MULERI, FABIO RANKIN, John SOFFITTA, PAOLO Veledina, Alexandra AMBROSINO, Filippo DEL SANTO, MELANIA Chen, Wei Garcia, Javier A. Kaaret, Philip Russell, Thomas D. Wei, Wen-Hao Zhang, Shuang-Nan Zuo, Chao Arzoumanian, Zaven COCCHI, Massimo Gnarini, Andrea FARINELLI, Ruben Gendreau, Keith Ursini, Francesco Weisskopf, Martin C. Zane, Silvia Agudo, Iván ANTONELLI, Lucio Angelo Baldini, Luca Baumgartner, Wayne H. Bellazzini, Ronaldo Bongiorno, Stephen D. Bonino, Raffaella Brez, Alessandro BUCCIANTINI, Niccolo' CAPITANIO, FIAMMA Castellano, Simone Cavazzuti, Elisabetta Chen, Chien-Ting Ciprini, Stefano DE ROSA, Alessandra DEL MONTE, Ettore Di Gesu, Laura Di Lalla, Niccolò Donnarumma, Immacolata Doroshenko, Victor Dovčiak, Michal Ehlert, Steven R. Enoto, Teruaki EVANGELISTA, YURI FABIANI, Sergio FERRAZZOLI, RICCARDO Gunji, Shuichi Hayashida, Kiyoshi Heyl, Jeremy Iwakiri, Wataru Jorstad, Svetlana G. Karas, Vladimir Kislat, Fabian Kitaguchi, Takao Kolodziejczak, Jeffery J. Latronico, Luca Liodakis, Ioannis Maldera, Simone Manfreda, Alberto Marin, Frédéric Marinucci, Andrea Marscher, Alan P. Marshall, Herman L. MASSARO, FRANCESCO Matt, Giorgio Mitsuishi, Ikuyuki Mizuno, Tsunefumi Negro, Michela Ng, Chi-Yung O'Dell, Stephen L. Omodei, Nicola Oppedisano, Chiara Pavlov, George G. Peirson, Abel L. PERRI, Matteo Pesce-Rollins, Melissa Petrucci, Pierre-Olivier POSSENTI, ANDREA Puccetti, Simonetta Ramsey, Brian D. |
Issue Date: | 2024 |
Journal: | THE ASTROPHYSICAL JOURNAL LETTERS |
Number: | 960 |
Issue: | 2 |
First Page: | L11 |
Abstract: | The Imaging X-ray Polarimetry Explorer measured with high significance the X-ray polarization of the brightest Z-source, Sco 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° at a 90% confidence level. This observation was strictly simultaneous with observations performed by NICER, NuSTAR, and Insight-HXMT, which allowed for a precise characterization of its broadband 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 quasiperiodic oscillations. From a spectropolarimetric analysis, we associate a polarization to the accretion disk at <3.2% at 90% confidence level, compatible with expectations for an electron scattering dominated optically thick atmosphere at the Sco X-1 inclination of ~44°; 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 a change in the corona geometry with the accretion flow. |
URI: | http://hdl.handle.net/20.500.12386/34822 |
URL: | https://iopscience.iop.org/article/10.3847/2041-8213/ad132d https://api.elsevier.com/content/abstract/scopus_id/85182388102 |
ISSN: | 2041-8205 |
DOI: | 10.3847/2041-8213/ad132d |
Bibcode ADS: | 2024ApJ...960L..11L |
Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista
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