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Lookup NU author(s): Dr Adam IngramORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2026. The Author(s). Published by the American Astronomical Society.We present the first IXPE spectro-polarimetric observation of the black hole candidate MAXI J1744−294, a transient X-ray source observed during a bright 2025 outburst in the Galactic center region. The source has recently been identified as most likely a repeat outburst of the 2016 transient Swift J174540.2−290037. During the ∼150 ks observation, the source was detected in the soft state, and its spectrum was well described by an absorbed multicolor disk with a minor high-energy tail. We did not detect any significant polarization from the source, and hence we derived a 3σ upper limit on the polarization degree of 1.3% in the 2-8 keV energy band. This result is consistent with previous findings for soft-state black hole binaries observed at low to intermediate inclination angles. By comparing the polarization degree upper limit with theoretical predictions for standard accretion disk emission, we constrain the disk inclination to i ≲ 38°-72°, depending on the black hole spin and the disk atmosphere albedo, consistent with inclination estimates obtained during the 2016 outburst of Swift J174540.2−290037.
Author(s): Marra L, Mikusincova R, Vincentelli FM, Capitanio F, Del Santo M, Fabiani S, Mandel S, Muleri F, Parra M, Soffitta P, Tarana A, Baglio MC, Bianchi S, Corbel S, Costa E, D'Ai A, De Marco B, Dovciak M, Gianolli VE, Gnarini A, Gupta M, Ingram A, Mastroserio G, Matt G, Mori K, Petrucci P-O, Podgorny J, Poutanen J, Steiner JF, Svoboda J, Taverna R, Tombesi F, Ravi S, Rodriguez J, Russell TD, Veledina A, Zhang S
Publication type: Article
Publication status: Published
Journal: Astrophysical Journal
Year: 2026
Volume: 1001
Issue: 2
Online publication date: 16/03/2026
Acceptance date: 15/04/2026
Date deposited: 28/04/2026
ISSN (print): 0004-637X
ISSN (electronic): 1538-4357
Publisher: American Astronomical Society
URL: https://doi.org/10.3847/1538-4357/ae5488
DOI: 10.3847/1538-4357/ae5488
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