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Evidence for Returning Disk Radiation in the Black Hole X-Ray Binary XTE J1550–564

Connors, Riley M. T. and García, Javier A. and Dauser, Thomas and Grinberg, Victoria and Steiner, James F. and Sridhar, Navin and Wilms, Jörn and Tomsick, John and Harrison, Fiona and Licklederer, Stefan (2020) Evidence for Returning Disk Radiation in the Black Hole X-Ray Binary XTE J1550–564. Astrophysical Journal, 892 (1). Art. No. 47. ISSN 1538-4357. doi:10.3847/1538-4357/ab7afc.

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We explore the accretion properties of the black hole X-ray binary XTE J1550−564 during its outbursts in 1998/99 and 2000. We model the disk, corona, and reflection components of X-ray spectra taken with the Rossi X-ray Timing Explorer, using the relxill suite of reflection models. The key result of our modeling is that the reflection spectrum in the very soft state is best explained by disk self-irradiation, i.e., photons from the inner disk are bent by the strong gravity of the black hole and reflected off the disk surface. This is the first known detection of thermal disk radiation reflecting off the inner disk. There is also an apparent absorption line at ~6.9 keV, which may be evidence of an ionized disk wind. The coronal electron temperature (kT_e) is, as expected, lower in the brighter outburst of 1998/99, explained qualitatively by more efficient coronal cooling due to irradiating disk photons. The disk inner radius is consistent with being within a few times the innermost stable circular orbit throughout the bright-hard-to-soft states (10 s of r_g in gravitational units). The disk inclination is low during the hard state, disagreeing with the binary inclination value, and very close to 90° in the soft state, recovering to a lower value when adopting a blackbody spectrum as the irradiating continuum.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Connors, Riley M. T.0000-0002-8908-759X
García, Javier A.0000-0003-3828-2448
Dauser, Thomas0000-0003-4583-9048
Grinberg, Victoria0000-0003-2538-0188
Steiner, James F.0000-0002-5872-6061
Sridhar, Navin0000-0002-5519-9550
Wilms, Jörn0000-0003-2065-5410
Tomsick, John0000-0001-5506-9855
Harrison, Fiona0000-0003-2992-8024
Licklederer, Stefan0000-0002-3720-4408
Additional Information:© 2020 The American Astronomical Society. Received 2019 December 31; revised 2020 February 21; accepted 2020 February 26; published 2020 March 27. We thank the referee for the diligent comments that helped to improve this paper. J.A.G. acknowledges support from NASA grant NNX15AV31G and from the Alexander von Humboldt Foundation. R.M.T.C. has been supported by NASA grant 80NSSC177K0515. V.G. is supported through the Margarete von Wrangell fellowship by the ESF and the Ministry of Science, Research and the Arts Baden-Württemberg. This research has made use of data, software and/or web tools obtained from the High Energy Astrophysics Science Archive Research Center (HEASARC), a service of the Astrophysics Science Division at NASA/GSFC and of the Smithsonian Astrophysical Observatory's High Energy Astrophysics Division. This research has made use of ISIS functions (ISISscripts) provided by ECAP/Remeis observatory and MIT ( Facilities: RXTE (PCA; Jahoda et al. 1996), HEASARC. Software: XSPEC v.12.10.1c (Arnaud 1996), XILLVER (García & Kallman 2010; García et al. 2013), RELXILL (v1.2.0; García et al. 2014; Dauser et al. 2014).
Group:Astronomy Department, Space Radiation Laboratory
Funding AgencyGrant Number
Alexander von Humboldt FoundationUNSPECIFIED
Margarete von Wrangell FellowshipUNSPECIFIED
European Social FundUNSPECIFIED
Ministry of Science, Research and the Arts (Baden-Württemberg)UNSPECIFIED
Subject Keywords:Accretion ; Astrophysical black holes ; black hole physics ; Kerr black holes ; Atomic physics ; Low-mass x-ray binary stars
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Accretion (14); Astrophysical black holes (98); Black hole physics (159); Kerr black holes (886); Atomic physics (2063); Low-mass x-ray binary stars (939)
Record Number:CaltechAUTHORS:20200327-150029432
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Official Citation:Riley M. T. Connors et al 2020 ApJ 892 47
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:102156
Deposited By: Tony Diaz
Deposited On:27 Mar 2020 22:08
Last Modified:16 Nov 2021 18:09

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