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Reflection Modeling of the Black Hole Binary 4U 1630–47: The Disk Density and Returning Radiation

Connors, Riley M. T. and García, Javier A. and Tomsick, John and Hare, Jeremy and Dauser, Thomas and Grinberg, Victoria and Steiner, James F. and Mastroserio, Guglielmo and Sridhar, Navin and Fabian, Andrew C. and Jiang, Jiachen and Parker, Michael L. and Harrison, Fiona and Kallman, Timothy R. (2021) Reflection Modeling of the Black Hole Binary 4U 1630–47: The Disk Density and Returning Radiation. Astrophysical Journal, 909 (2). Art. No. 146. ISSN 1538-4357.

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We present the analysis of X-ray observations of the black hole binary 4U 1630−47 using relativistic reflection spectroscopy. We use archival data from the Rossi X-ray Timing Explorer, Neil Gehrels Swift Observatory, and Nuclear Spectroscopic Telescope Array observatories, taken during different outbursts of the source between 1998 and 2015. Our modeling includes two relatively new advances in modern reflection codes: high-density disks, and returning thermal disk radiation. Accretion disks around stellar-mass black holes are expected to have densities well above the standard value assumed in traditional reflection models (i.e., ne ~ 10¹⁵ cm⁻³). New high-density reflection models have important implications in the determination of disk truncation (i.e., the disk inner radius). This is because one must retain self-consistency in the irradiating flux and corresponding disk ionization state, which is a function of disk density and system geometry. We find that the disk density is n_e ≥ 10²⁰ cm⁻³ across all spectral states. This density, combined with our constraints on the ionization state of the material, implies an irradiating flux impinging on the disk that is consistent with the expected theoretical estimates. Returning thermal disk radiation—the fraction of disk photons that bend back to the disk producing additional reflection components—is expected predominantly in the soft state. We show that returning radiation models indeed provide a better fit to the soft-state data, reinforcing previous results that show that in the soft state, the irradiating continuum may be blackbody emission from the disk itself.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Connors, Riley M. T.0000-0002-8908-759X
García, Javier A.0000-0003-3828-2448
Tomsick, John0000-0001-5506-9855
Hare, Jeremy0000-0002-8548-482X
Dauser, Thomas0000-0003-4583-9048
Grinberg, Victoria0000-0003-2538-0188
Steiner, James F.0000-0002-5872-6061
Mastroserio, Guglielmo0000-0003-4216-7936
Sridhar, Navin0000-0002-5519-9550
Fabian, Andrew C.0000-0002-9378-4072
Jiang, Jiachen0000-0002-9639-4352
Parker, Michael L.0000-0002-8466-7317
Harrison, Fiona0000-0003-2992-8024
Kallman, Timothy R.0000-0002-5779-6906
Additional Information:© 2021. The American Astronomical Society. Received 2020 October 14; revised 2021 January 14; accepted 2021 January 15; published 2021 March 12. We thank the referee for the helpful comments, each of which facilitated the improvement of this manuscript. This work was partially supported under NASA contract No. NNG08FD60C and made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. We thank the NuSTAR Operations, Software, and Calibration teams for support with the execution and analysis of these observations. This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS), jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). R.M.T.C. has been supported by NASA ADAP grant 80NSSC177K0515. J.A.G. acknowledges support from NASA APRA grant 80NSSC17K0345 and from the Alexander von Humboldt Foundation. V.G. is supported through the Margarete von Wrangell fellowship by the ESF and the Ministry of Science, Research and the Arts Baden-Württemberg. J.A.T. acknowledges partial support from NASA ADAP grant 80NSSC19K0586. J.H. acknowledges support from an appointment to the NASA Postdoctoral Program at the Goddard Space Flight Center, administered by the USRA through a contract with NASA. 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 ( Facility: RXTE - Rossi X-ray Timing Explorer (PCA; Jahoda et al. 1996), NuSTAR(Harrison et al. 2013), Swift-XRT (Krimm et al. 2013), HEASARC. Software: XSPEC v.12.10.1s (Arnaud 1996), REFLIONX (Ross & Fabian 2005, 2007), XILLVER (García & Kallman 2010; García et al. 2013), RELXILL (v1.3.3; Dauser et al. 2014; García et al. 2014), PCACORR (García et al. 2014).
Group:Astronomy Department, Space Radiation Laboratory
Funding AgencyGrant Number
Alexander von Humboldt FoundationUNSPECIFIED
Margarete von Wrangell FellowshipUNSPECIFIED
Baden-Württemberg Ministry of Science, Research and the ArtsUNSPECIFIED
Subject Keywords:Accretion; Stellar accretion disks; Black hole physics; Atomic physics; Low-mass x-ray binary stars
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Accretion (14); Stellar accretion disks (1579); Black hole physics (159); Atomic physics (2063); Low-mass x-ray binary stars (939)
Record Number:CaltechAUTHORS:20210309-080810844
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108358
Deposited By: Tony Diaz
Deposited On:10 Mar 2021 20:00
Last Modified:12 Mar 2021 21:47

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