Exploring MAXI J1744−294: IXPE Insights into a Galactic Center X-Ray Transient

Abstract 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 3 σ 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.

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Journal
The Astrophysical Journal
Published
2026-04-15
DOI
https://doi.org/10.3847/1538-4357/ae5488
Primary Topic
Astrophysical Phenomena and Observations
Type
article
Field-Weighted Citation Impact
0.00

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article

Exploring MAXI J1744−294: IXPE Insights into a Galactic Center X-Ray Transient

F. Vincentelli, Jiří Svoboda, Juri Poutanen, Michal Dovčiak et al.
The Astrophysical Journal
Astrophysical Phenomena and Observations
article

Exploring MAXI J1744−294: IXPE Insights into a Galactic Center X-Ray Transient

F. Vincentelli, Jiří Svoboda, Juri Poutanen, Michal Dovčiak, A. D’Aí, E. Costa, G. Matt, P O Petrucci, Adam Ingram, Lorenzo Marra, Fiamma Capitanio, Maxime Parra, A. Tarana, Andrea Gnarini, Jakub Podgorný, Fabio Muleri, Romana Mikušincová, Roberto Taverna, Sergio Fabiani, Barbara De Marco, V. E. Gianolli, Guglielmo Mastroserio, James F. Steiner, M. C. Baglio, Shifra Mandel, Alexandra Veledina, S. Bianchi, Shuo Zhang, Swati Ravi, Maitrayee Gupta, F Tombesi, M. Del Santo, P Soffitta, Jerome Rodriguez, Kaya Mori, S Corbel, T D Russell
article en

Abstract

Abstract 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 3 σ 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.

The Astrophysical JournalVol. 1001(2)
University of Rome Tor Vergata (IT), Roma Tre University (IT), Marshall Space Flight Center (US), Centre National de la Recherche Scientifique (FR), University of Padua (IT), University of Turku (FI), Stockholm University (SE), University of Milan (IT), Université Paris Cité (FR), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR), Université Paris-Saclay (FR), Czech Academy of Sciences, Astronomical Institute (CZ), Brera Astronomical Observatory (IT), Astrophysique, Instrumentation et Modélisation (FR), Kavli Institute for Particle Astrophysics and Cosmology (US), Institute for Space Astrophysics and Planetology (IT), Institut de Planétologie et d'Astrophysique de Grenoble (FR), Center for Astrophysics Harvard & Smithsonian (US), CEA Paris-Saclay (FR), Istituto di Astrofisica Spaziale e Fisica cosmica di Palermo (IT), Astronomical Institute of the Slovak Academy of Sciences (SK), Istituto Nazionale di Fisica Nucleare, Sezione di Milano (IT), Unité d'Appui et de Recherche OSUPS (FR), Ehime University (JP), Columbia University (US), Clemson University (US), Newcastle University (GB), KTH Royal Institute of Technology (SE), Michigan State University (US), Université Grenoble Alpes (FR), Universitat Politècnica de Catalunya (ES)
Smithsonian Institution, National Aeronautics and Space Administration, Oak Ridge Associated Universities, European Commission, Grantová Agentura České Republiky, Centre National d’Etudes Spatiales, Agenzia Spaziale Italiana, NordForsk, Centre National de la Recherche Scientifique, Istituto Nazionale di Astrofisica, Istituto Nazionale di Fisica Nucleare, Marshall Space Flight Center, Goddard Space Flight Center, Smithsonian Astrophysical Observatory, HORIZON EUROPE Framework Programme
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