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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).
© 2024. The Author(s). Published by the American Astronomical Society. MAXI J1803-298 is a transient black hole candidate discovered in 2021 May during an outburst that lasted several months. Multiple X-ray observations reveal recurring “dipping” intervals in several of its light curves, particularly during the hard/intermediate states, with a typical recurrence period of ∼7 hr. We report analysis of four NuSTAR observations of the source, supplemented with NICER data where available, over the duration of the outburst evolution covering the hard, intermediate, and the soft states. Reflection spectroscopy reveals the black hole to be rapidly spinning (a* = 0.990 ± 0.001) with a near edge-on viewing angle (i = 70° ± 1°). Additionally, we show that the light-curve dips are caused by photoelectric absorption from a moderately ionized absorber whose origin is not fully understood, although it is likely linked to material from the companion star impacting the outer edges of the accretion disk. We further detect absorption lines in some of the spectra, potentially associated with Fe xxv and Fe xxvi, indicative of disk winds with moderate to extreme velocities. During the intermediate state and just before transitioning into the soft state, the source showed a sudden flux increase, which we found to be dominated by soft disk photons and consistent with the filling of the inner accretion disk, at the onset of state transition. In the soft state, we show that models of disk self-irradiation provide a better fit and a preferred explanation to the broadband reflection spectrum, consistent with previous studies of other accreting sources.
Author(s): Adegoke OK, Garcia JA, Connors RMT, Ding Y, Mastroserio G, Steiner JF, Ingram A, Harrison FA, Tomsick JA, Kara E, Mehdipour M, Fukumura K, Stern D, Ubach S, Lucchini M
Publication type: Article
Publication status: Published
Journal: Astrophysical Journal
Year: 2024
Volume: 977
Online publication date: 29/11/2024
Acceptance date: 01/10/2024
Date deposited: 09/12/2024
ISSN (print): 0004-637X
ISSN (electronic): 1538-4357
Publisher: Institute of Physics Publishing Ltd
URL: https://doi.org/10.3847/1538-4357/ad82e9
DOI: 10.3847/1538-4357/ad82e9
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