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Title: STRONGER REFLECTION FROM BLACK HOLE ACCRETION DISKS IN SOFT X-RAY STATES

Abstract

We analyze 15,000 spectra of 29 stellar-mass black hole (BH) candidates collected over the 16 year mission lifetime of Rossi X-ray Timing Explorer using a simple phenomenological model. As these BHs vary widely in luminosity and progress through a sequence of spectral states, which we broadly refer to as hard and soft, we focus on two spectral components: the Compton power law and the reflection spectrum it generates by illuminating the accretion disk. Our proxy for the strength of reflection is the equivalent width of the Fe–K line as measured with respect to the power law. A key distinction of our work is that for all states we estimate the continuum under the line by excluding the thermal disk component and using only the component that is responsible for fluorescing the Fe–K line, namely, the Compton power law. We find that reflection is several times more pronounced (∼3) in soft compared to hard spectral states. This is most readily caused by the dilution of the Fe line amplitude from Compton scattering in the corona, which has a higher optical depth in hard states. Alternatively, this could be explained by a more compact corona in soft (compared to hard) states, whichmore » would result in a higher reflection fraction.« less

Authors:
;  [1]; ;  [2]
  1. MIT Kavli Institute for Astrophysics and Space Research, MIT, 70 Vassar Street, Cambridge, MA 02139 (United States)
  2. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
Publication Date:
OSTI Identifier:
22654217
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 829; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; AMPLITUDES; BLACK HOLES; COMPARATIVE EVALUATIONS; COMPTON EFFECT; DILUTION; LIFETIME; LUMINOSITY; MASS; REFLECTION; SOFT X RADIATION; SPECTRA; FUNDAMENTAL INTERACTIONS

Citation Formats

Steiner, James F., Remillard, Ronald A., García, Javier A., and McClintock, Jeffrey E., E-mail: jsteiner@mit.edu. STRONGER REFLECTION FROM BLACK HOLE ACCRETION DISKS IN SOFT X-RAY STATES. United States: N. p., 2016. Web. doi:10.3847/2041-8205/829/2/L22.
Steiner, James F., Remillard, Ronald A., García, Javier A., & McClintock, Jeffrey E., E-mail: jsteiner@mit.edu. STRONGER REFLECTION FROM BLACK HOLE ACCRETION DISKS IN SOFT X-RAY STATES. United States. doi:10.3847/2041-8205/829/2/L22.
Steiner, James F., Remillard, Ronald A., García, Javier A., and McClintock, Jeffrey E., E-mail: jsteiner@mit.edu. Sat . "STRONGER REFLECTION FROM BLACK HOLE ACCRETION DISKS IN SOFT X-RAY STATES". United States. doi:10.3847/2041-8205/829/2/L22.
@article{osti_22654217,
title = {STRONGER REFLECTION FROM BLACK HOLE ACCRETION DISKS IN SOFT X-RAY STATES},
author = {Steiner, James F. and Remillard, Ronald A. and García, Javier A. and McClintock, Jeffrey E., E-mail: jsteiner@mit.edu},
abstractNote = {We analyze 15,000 spectra of 29 stellar-mass black hole (BH) candidates collected over the 16 year mission lifetime of Rossi X-ray Timing Explorer using a simple phenomenological model. As these BHs vary widely in luminosity and progress through a sequence of spectral states, which we broadly refer to as hard and soft, we focus on two spectral components: the Compton power law and the reflection spectrum it generates by illuminating the accretion disk. Our proxy for the strength of reflection is the equivalent width of the Fe–K line as measured with respect to the power law. A key distinction of our work is that for all states we estimate the continuum under the line by excluding the thermal disk component and using only the component that is responsible for fluorescing the Fe–K line, namely, the Compton power law. We find that reflection is several times more pronounced (∼3) in soft compared to hard spectral states. This is most readily caused by the dilution of the Fe line amplitude from Compton scattering in the corona, which has a higher optical depth in hard states. Alternatively, this could be explained by a more compact corona in soft (compared to hard) states, which would result in a higher reflection fraction.},
doi = {10.3847/2041-8205/829/2/L22},
journal = {Astrophysical Journal Letters},
number = 2,
volume = 829,
place = {United States},
year = {Sat Oct 01 00:00:00 EDT 2016},
month = {Sat Oct 01 00:00:00 EDT 2016}
}