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

Connors RMT, Garcia JA, Tomsick J, Hare J, Dauser T, Grinberg V, Steiner JF, Mastroserio G, Sridhar N, Fabian AC, Jiang J, Parker ML, Harrison F, Kallman TR (2021)

Publication Type: Journal article

Publication year: 2021

Journal

Astrophysical Journal American Astronomical Society

Book Volume: 909

Article Number: 146

Journal Issue: 2

DOI: 10.3847/1538-4357/abdd2c

Abstract

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., n e ∼ 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.

Authors with CRIS profile

Thomas Dauser Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut

Involved external institutions

California Institute of Technology (Caltech) US United States (USA) (US) University of California, Berkeley US United States (USA) (US) National Aeronautics and Space Administration (NASA) US United States (USA) (US) Eberhard Karls Universität Tübingen DE Germany (DE) Harvard-Smithsonian Center for Astrophysics (CfA) US United States (USA) (US) Columbia University US United States (USA) (US) University of Cambridge GB United Kingdom (GB) Tsinghua University CN China (CN) European Space Astronomy Centre (ESAC) ES Spain (ES)

How to cite

APA:

Connors, R.M.T., Garcia, J.A., Tomsick, J., Hare, J., Dauser, T., Grinberg, V.,... Kallman, T.R. (2021). Reflection Modeling of the Black Hole Binary 4U 1630-47: The Disk Density and Returning Radiation. Astrophysical Journal, 909(2). https://dx.doi.org/10.3847/1538-4357/abdd2c

MLA:

Connors, Riley M. T., et al. "Reflection Modeling of the Black Hole Binary 4U 1630-47: The Disk Density and Returning Radiation." Astrophysical Journal 909.2 (2021).

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