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Broadband X-ray Spectral and Timing Analyses of the Black Hole Binary Candidate Swift J1658.2-4242: Rapid Flux Variation and the Turn-on of a Transient QPO

Xu, Yanjun and Harrison, Fiona A. and Tomsick, John A. and Barret, Didier and Gandhi, Poshak and García, Javier A. and Miller, Jon M. and Uttley, Phil and Walton, Dominic J. (2019) Broadband X-ray Spectral and Timing Analyses of the Black Hole Binary Candidate Swift J1658.2-4242: Rapid Flux Variation and the Turn-on of a Transient QPO. Astrophysical Journal, 879 (2). Art. No. 93. ISSN 1538-4357. doi:10.3847/1538-4357/ab24bf.

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We report results from joint Nuclear Spectroscopic Telescope Array, Swift, and XMM-Newton observations of the newly discovered black hole X-ray binary candidate Swift J1658.2–4242 in the intermediate state. We observe a peculiar event in this source, with its X-ray flux rapidly decreasing by ~45% in ~40 s, accompanied by only subtle changes in the shape of the broadband X-ray spectrum. In addition, we find a sudden turn-on of a transient quasi-periodic oscillation (QPO) with a frequency of 6–7 Hz around the time of the flux change, and the total fractional rms amplitude of the power spectrum increases from ~2% to ~10%. The X-ray spectral and timing analyses indicate that the flux decrease is driven by intrinsic changes in the accretion flow around the black hole, rather than intervening material along the line of sight. In addition, we do not significantly detect any relativistic disk reflection component, indicating it is much weaker than previously observed while the source was in the bright hard state. We propose accretion disk instabilities triggered at a large disk radius as the origin of the fast transition in spectral and timing properties, and discuss possible causes of the unusual properties observed in Swift J1658.2–4242. The prompt flux variation detected along with the emergence of a QPO makes the event an interesting case for investigating QPO mechanisms in black hole X-ray binaries.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Xu, Yanjun0000-0003-2443-3698
Harrison, Fiona A.0000-0003-2992-8024
Tomsick, John A.0000-0001-5506-9855
Barret, Didier0000-0002-0393-9190
Gandhi, Poshak0000-0003-3105-2615
García, Javier A.0000-0003-3828-2448
Walton, Dominic J.0000-0001-5819-3552
Additional Information:© 2019 The American Astronomical Society. Received 2019 February 27; revised 2019 May 1; accepted 2019 May 23; published 2019 July 10. We thank the anonymous referee for the helpful comments that improved the paper. We thank Tom Russell and James Miller-Jones for providing information about ATCA radio observations. D.J.W. acknowledges support from the STFC Ernest Rutherford Fellowship. This work was 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). This research has also made use of data obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States, and Swift, a NASA mission with participation of the Italian Space Agency (ASI) and the Particle Physics and Astronomy Research Council in the United Kingdom.
Group:NuSTAR, Space Radiation Laboratory, Astronomy Department
Funding AgencyGrant Number
Science and Technology Facilities Council (STFC)UNSPECIFIED
Subject Keywords:accretion, accretion disks – X-rays: binaries – X-rays: individual (Swift J1658.2-4242)
Issue or Number:2
Record Number:CaltechAUTHORS:20190619-085644567
Persistent URL:
Official Citation:Yanjun Xu et al 2019 ApJ 879 93
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:96517
Deposited By: Tony Diaz
Deposited On:19 Jun 2019 17:10
Last Modified:16 Nov 2021 17:21

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