Super-Eddington accretion geometry : a remarkable stability of the hidden ultraluminous X-ray source Cygnus X-3;
: Mikušincová, Romana; Veledina, Alexandra; Muleri, Fabio; Ciancarella, Raul; Zdziarski, Andrzej; Green, David A.; McCollough, Michael; Krawczynski, Henric; Steiner, James F.; Dovčiak, Michal; Ahlberg, Varpu; Bianchi, Stefano; Di Marco, Alessandro; García, Javier A.; Ingram, Adam; Kaaret, Philip; Kallman, Timothy; Kun, Hu; La Monaca, Fabio; Lange, Alexander; Loktev, Vladislav; Mastroserio, Guglielmo; Matt, Giorgio; Emami, Razieh; Petrucci, Pierre-Olivier; Podgorný, Jakub; Poutanen, Juri; Ratheesh, Ajay; Rodriguez, Nicole; Svoboda, Jiří; Tombesi, Francesco; Ursini, Francesco; Agudo, Iván; Antonelli, Lucio A.; Bachetti, Matteo; Baldini, Luca; Baumgartner, Wayne H.; Bellazzini, Ronaldo; Bongiorno, Stephen D.; Bonino, Raffaella; Brez, Alessandro; Bucciantini, Niccolò; Capitanio, Fiamma; Castellano, Simone; Cavazzuti, Elisabetta; Chen, Chien-Ting; Ciprini, Stefano; Costa, Enrico; De Rosa, Alessandra; Del Monte, Ettore; Di Gesu, Laura; Di Lalla, Niccolò; Donnarumma, Immacolata; Doroshenko, Victor; 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; Mitsuishi, Ikuyuki; Mizuno, Tsunefumi; Negro, Michela; Yung, Ng Chi-; O’Dell, Stephen L.; Omodei, Nicola; Oppedisano, Chiara; Papitto, Alessandro; Pavlov, George G.; Peirson, Abel L.; Perri, Matteo; Pesce-Rollins, Melissa; Pilia, Maura; Possenti, Andrea; Puccetti, Simonetta; Ramsey, Brian D.; Rankin, John; Roberts, Oliver J.; Romani, Roger W.; Sgrò, Carmelo; Slane, Patrick; Soffitta, Paolo; Spandre, Gloria; Swartz, Douglas A.; Tamagawa, Toru; Tavecchio, Fabrizio; Taverna, Roberto; Tawara, Yuzuru; Tennant, Allyn F.; Thomas, Nicholas E.; Trois, Alessio; Tsygankov, Sergey S.; Turolla, Roberto; Vink, Jacco; Weisskopf, Martin C.; Wu, Kinwah; Xie, Fei; Zane, Silvia
Publisher: Institute of Physics Publishing
: 2026
Astrophysical Journal
: 83
: 1005
: 1
: 0004-637X
: 1538-4357
DOI: https://doi.org/10.3847/1538-4357/ae7366
: https://doi.org/10.3847/1538-4357/ae7366
: https://research.utu.fi/converis/portal/detail/Publication/527169922
We report on the average and orbital phase-resolved polarization of Cyg X-3 in the hard state (HS) during the 2023 Imaging X-ray Polarimetry Explorer (IXPE) observational campaign. We find the polarization degree of 21.4% ± 0.4% and polarization angle of 92°.2 ± 0°.5, compatible within 3σ with the first HS IXPE observation in 2022. As the observed polarization depends on both the accretion geometry and the X-ray emission mechanism, and assuming it arises from reflection from the optically thick envelope surrounding the central source, our result indicates that both are similar in the two HS epochs on year-long timescales despite the source transitioning through an intermediate state in between. We discuss time- and energy-dependent polarization properties and their implications for the geometry and stability of the accretion funnel, finding significant orbital modulation of the polarization properties.
accretion, polarimetry, stellar mass black holes, X-ray astronomy, X-ray binary stars
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The Imaging X-ray Polarimetry Explorer (IXPE) is a joint US and Italian mission. The US contribution is supported by the National Aeronautics and Space Administration (NASA) and led and managed by its Marshall Space Flight Center (MSFC), with industry partner Ball Aerospace (contract NNM15AA18C). The Italian contribution is supported by the Italian Space Agency (Agenzia Spaziale Italiana, ASI) through contract ASI-OHBI-2022-13-I.0, agreements ASI-INAF-2022-19-HH.1-2026 and ASI-INFN-2017.13-H0, and its Space Science Data Center (SSDC) with agreements ASI-INAF 2025-33-HH.0 and ASI-INFN 2026-5-HH.0, and by the Istituto Nazionale di Astrofisica (INAF) and the Istituto Nazionale di Fisica Nucleare (INFN) in Italy. This research used data products provided by the IXPE Team (MSFC, SSDC, INAF, and INFN) and distributed with additional software tools by the High-Energy Astrophysics Science Archive Research Center (HEASARC) at NASA Goddard Space Flight Center (GSFC).
A.V. acknowledges support from the Academy of Finland grant 355672. Nordita is supported in part by NordForsk. A.A.Z. acknowledges support from the Polish National Science Center grants 2019/35/B/ST9/03944 and 2023/48/Q/ST9/00138. M.D. and J.S. thank GACR project 21-06825X for the support and institutional support from RVO:67985815. The work of G.M. is partially supported by the PRIN 2022—2022LWPEXW—“An X-ray view of compact objects in polarized light,” CUP C53D23001180006. A.I. acknowledges support from the Royal Society. P.O.P. acknowledges financial support from the French Space National Agency (CNES) and the National Center of Scientific Research (CNRS) via its “Action Thématique” PEM. J.P. acknowledges institutional support from RVO:67985815. I.L. was funded by the European Union ERC-2022-STG-BOOTES-101076343. Views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council Executive Agency. Neither the European Union nor the granting authority can be held responsible for them.
