The Hard State of the Highly Absorbed High Inclination Black Hole Binary Candidate Swift J1658.2-4242 Observed by NuSTAR and Swift

Yanjun Xu, Fiona A. Harrison, Jamie A. Kennea, Dominic J. Walton, John A. Tomsick, Jon M. Miller, Didier Barret, Andrew C. Fabian, Karl Forster, Felix Fürst, Poshak Gandhi, Javier A. Garcia

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Abstract

We present a spectral and timing analysis of the newly reported Galactic X-ray transient Swift J1658.2-4242 observed by Nuclear Spectroscopic Telescope Array (NuSTAR) and Swift. The broadband X-ray continuum is typical of a black hole binary in the bright hard state, with a photon index of Γ = 1.63 ± 0.02 and a low coronal temperature of kT e = 22 ±1 keV, corresponding to a low spectral cutoff well constrained by NuSTAR. Spectral modeling of the relativistic disk reflection features, consisting of a broad Fe K line and the Compton reflection hump, reveals that the black hole is rapidly spinning with the spin parameter of a∗ > 0.96, and the inner accretion disk is viewed at a high inclination angle of i = 64+2° 3 (statistical errors, 90% confidence). The high inclination is independently confirmed by dips in the light curves, which can be explained by absorbing material located near the disk plane temporarily obscuring the central region. In addition, we detect an absorption line in the NuSTAR spectra centered at 7.03+0.0.4 -0.03 keV. If associated with ionized Fe K absorption lines, this provides evidence for the presence of outflowing material in the low/hard state of a black hole binary candidate. A timing analysis shows the presence of a type-C quasi-periodic oscillation in the power spectrum, with the frequency increasing from ∼0.14 to ∼0.21 Hz during the single NuSTAR exposure. Our analysis reveals that Swift J1658.2-4242 displays characteristics typical for a black hole binary that is viewed at a high inclination angle, making it a good system for studying the accretion geometry in black hole binaries.

Original languageEnglish (US)
Article number18
JournalAstrophysical Journal
Volume865
Issue number1
DOIs
StatePublished - Sep 20 2018

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spectroscopic telescopes
inclination
accretion
time measurement
K lines
dip
accretion disks
oscillation
metal spinning
light curve
spectrum analysis
power spectra
confidence
geometry
x rays
cut-off
continuums
broadband
oscillations
modeling

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Xu, Yanjun ; Harrison, Fiona A. ; Kennea, Jamie A. ; Walton, Dominic J. ; Tomsick, John A. ; Miller, Jon M. ; Barret, Didier ; Fabian, Andrew C. ; Forster, Karl ; Fürst, Felix ; Gandhi, Poshak ; Garcia, Javier A. / The Hard State of the Highly Absorbed High Inclination Black Hole Binary Candidate Swift J1658.2-4242 Observed by NuSTAR and Swift. In: Astrophysical Journal. 2018 ; Vol. 865, No. 1.
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abstract = "We present a spectral and timing analysis of the newly reported Galactic X-ray transient Swift J1658.2-4242 observed by Nuclear Spectroscopic Telescope Array (NuSTAR) and Swift. The broadband X-ray continuum is typical of a black hole binary in the bright hard state, with a photon index of Γ = 1.63 ± 0.02 and a low coronal temperature of kT e = 22 ±1 keV, corresponding to a low spectral cutoff well constrained by NuSTAR. Spectral modeling of the relativistic disk reflection features, consisting of a broad Fe K line and the Compton reflection hump, reveals that the black hole is rapidly spinning with the spin parameter of a∗ > 0.96, and the inner accretion disk is viewed at a high inclination angle of i = 64+2° 3 (statistical errors, 90{\%} confidence). The high inclination is independently confirmed by dips in the light curves, which can be explained by absorbing material located near the disk plane temporarily obscuring the central region. In addition, we detect an absorption line in the NuSTAR spectra centered at 7.03+0.0.4 -0.03 keV. If associated with ionized Fe K absorption lines, this provides evidence for the presence of outflowing material in the low/hard state of a black hole binary candidate. A timing analysis shows the presence of a type-C quasi-periodic oscillation in the power spectrum, with the frequency increasing from ∼0.14 to ∼0.21 Hz during the single NuSTAR exposure. Our analysis reveals that Swift J1658.2-4242 displays characteristics typical for a black hole binary that is viewed at a high inclination angle, making it a good system for studying the accretion geometry in black hole binaries.",
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Xu, Y, Harrison, FA, Kennea, JA, Walton, DJ, Tomsick, JA, Miller, JM, Barret, D, Fabian, AC, Forster, K, Fürst, F, Gandhi, P & Garcia, JA 2018, 'The Hard State of the Highly Absorbed High Inclination Black Hole Binary Candidate Swift J1658.2-4242 Observed by NuSTAR and Swift', Astrophysical Journal, vol. 865, no. 1, 18. https://doi.org/10.3847/1538-4357/aada03

The Hard State of the Highly Absorbed High Inclination Black Hole Binary Candidate Swift J1658.2-4242 Observed by NuSTAR and Swift. / Xu, Yanjun; Harrison, Fiona A.; Kennea, Jamie A.; Walton, Dominic J.; Tomsick, John A.; Miller, Jon M.; Barret, Didier; Fabian, Andrew C.; Forster, Karl; Fürst, Felix; Gandhi, Poshak; Garcia, Javier A.

In: Astrophysical Journal, Vol. 865, No. 1, 18, 20.09.2018.

Research output: Contribution to journalArticle

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T1 - The Hard State of the Highly Absorbed High Inclination Black Hole Binary Candidate Swift J1658.2-4242 Observed by NuSTAR and Swift

AU - Xu, Yanjun

AU - Harrison, Fiona A.

AU - Kennea, Jamie A.

AU - Walton, Dominic J.

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AU - Barret, Didier

AU - Fabian, Andrew C.

AU - Forster, Karl

AU - Fürst, Felix

AU - Gandhi, Poshak

AU - Garcia, Javier A.

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N2 - We present a spectral and timing analysis of the newly reported Galactic X-ray transient Swift J1658.2-4242 observed by Nuclear Spectroscopic Telescope Array (NuSTAR) and Swift. The broadband X-ray continuum is typical of a black hole binary in the bright hard state, with a photon index of Γ = 1.63 ± 0.02 and a low coronal temperature of kT e = 22 ±1 keV, corresponding to a low spectral cutoff well constrained by NuSTAR. Spectral modeling of the relativistic disk reflection features, consisting of a broad Fe K line and the Compton reflection hump, reveals that the black hole is rapidly spinning with the spin parameter of a∗ > 0.96, and the inner accretion disk is viewed at a high inclination angle of i = 64+2° 3 (statistical errors, 90% confidence). The high inclination is independently confirmed by dips in the light curves, which can be explained by absorbing material located near the disk plane temporarily obscuring the central region. In addition, we detect an absorption line in the NuSTAR spectra centered at 7.03+0.0.4 -0.03 keV. If associated with ionized Fe K absorption lines, this provides evidence for the presence of outflowing material in the low/hard state of a black hole binary candidate. A timing analysis shows the presence of a type-C quasi-periodic oscillation in the power spectrum, with the frequency increasing from ∼0.14 to ∼0.21 Hz during the single NuSTAR exposure. Our analysis reveals that Swift J1658.2-4242 displays characteristics typical for a black hole binary that is viewed at a high inclination angle, making it a good system for studying the accretion geometry in black hole binaries.

AB - We present a spectral and timing analysis of the newly reported Galactic X-ray transient Swift J1658.2-4242 observed by Nuclear Spectroscopic Telescope Array (NuSTAR) and Swift. The broadband X-ray continuum is typical of a black hole binary in the bright hard state, with a photon index of Γ = 1.63 ± 0.02 and a low coronal temperature of kT e = 22 ±1 keV, corresponding to a low spectral cutoff well constrained by NuSTAR. Spectral modeling of the relativistic disk reflection features, consisting of a broad Fe K line and the Compton reflection hump, reveals that the black hole is rapidly spinning with the spin parameter of a∗ > 0.96, and the inner accretion disk is viewed at a high inclination angle of i = 64+2° 3 (statistical errors, 90% confidence). The high inclination is independently confirmed by dips in the light curves, which can be explained by absorbing material located near the disk plane temporarily obscuring the central region. In addition, we detect an absorption line in the NuSTAR spectra centered at 7.03+0.0.4 -0.03 keV. If associated with ionized Fe K absorption lines, this provides evidence for the presence of outflowing material in the low/hard state of a black hole binary candidate. A timing analysis shows the presence of a type-C quasi-periodic oscillation in the power spectrum, with the frequency increasing from ∼0.14 to ∼0.21 Hz during the single NuSTAR exposure. Our analysis reveals that Swift J1658.2-4242 displays characteristics typical for a black hole binary that is viewed at a high inclination angle, making it a good system for studying the accretion geometry in black hole binaries.

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