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Super-Eddington Accretion Geometry: A Remarkable Stability of the Hidden Ultraluminous X-Ray Source Cygnus X-3

Lookup NU author(s): Dr Adam Ingram, Dr Vladislav LoktevORCiD

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).

Abstract

© 2026. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the https://creativecommons.org/licenses/by/4.0/. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.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 (Formula presented) 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.

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Author(s): Mikusincova R, Veledina A, Muleri F, Ciancarella R, Zdziarski A, Green DA, McCollough M, Krawczynski H, Steiner JF, Dovciak M, Ahlberg V, Bianchi S, Di Marco A, Garcia JA, Ingram A, Kaaret P, Kallman T, Kun H, La Monaca F, Lange A, Loktev V, Mastroserio G, Matt G, Emami R, Petrucci P-O, Podgorny J, Poutanen J, Ratheesh A, Rodriguez N, Svoboda J, Tombesi F, Ursini F, Agudo I, Antonelli LA, Bachetti M, Baldini L, Baumgartner WH, Bellazzini R, Bongiorno SD, Bonino R, Brez A, Bucciantini N, Capitanio F, Castellano S, Cavazzuti E, Chen C-T, Ciprini S, Costa E, De Rosa A, Del Monte E, Di Gesu L, Di Lalla N, Donnarumma I, Doroshenko V, Ehlert SR, Enoto T, Evangelista Y, Fabiani S, Ferrazzoli R, Gunji S, Hayashida K, Heyl J, Iwakiri W, Jorstad SG, Karas V, Kislat F, Kitaguchi T, Kolodziejczak JJ, Latronico L, Liodakis I, Maldera S, Manfreda A, Marin F, Marinucci A, Marscher AP, Marshall HL, Massaro F, Mitsuishi I, Mizuno T, Negro M, Yung Ng C, O'Dell SL, Omodei N, Oppedisano C, Papitto A, Pavlov GG, Peirson AL, Perri M, Pesce-Rollins M, Pilia M, Possenti A, Puccetti S, Ramsey BD, Rankin J, Roberts OJ, Romani RW, Sgro C, Slane P, Soffitta P, Spandre G, Swartz DA, Tamagawa T, Tavecchio F, Taverna R, Tawara Y, Tennant AF, Thomas NE, Trois A, Tsygankov SS, Turolla R, Vink J, Weisskopf MC, Wu K, Xie F, Zane S

Publication type: Article

Publication status: Published

Journal: Astrophysical Journal

Year: 2026

Volume: 1005

Issue: 1

Online publication date: 26/06/2026

Acceptance date: 25/05/2026

Date deposited: 17/07/2026

ISSN (print): 0004-637X

ISSN (electronic): 1538-4357

Publisher: American Astronomical Society

URL: https://doi.org/10.3847/1538-4357/ae7366

DOI: 10.3847/1538-4357/ae7366

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