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The 2017 Failed Outburst of GX 339-4: Relativistic X-ray Reflection near the Black Hole Revealed by NuSTAR and Swift Spectroscopy

García, Javier A. and Tomsick, John A. and Sridhar, Navin and Grinberg, Victoria and Connors, Riley M. T. and Wang, Jingyi and Steiner, James F. and Dauser, Thomas and Walton, Dominic J. and Xu, Yanjun and Harrison, Fiona A. and Foster, Karl and Grefenstette, Brian and Madsen, Kristin and Fabian, Andrew (2019) The 2017 Failed Outburst of GX 339-4: Relativistic X-ray Reflection near the Black Hole Revealed by NuSTAR and Swift Spectroscopy. Astrophysical Journal, 885 (1). Art. No. 48. ISSN 1538-4357. doi:10.3847/1538-4357/ab384f.

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We report on the spectroscopic analysis of the black hole binary GX 339−4 during its recent 2017–2018 outburst, observed simultaneously by the Swift and NuSTAR observatories. Although during this particular outburst the source failed to make state transitions, and despite Sun constraints during the peak luminosity, we were able to trigger four different observations sampling the evolution of the source in the hard state. We show that even for the lowest-luminosity observations the NuSTAR spectra show clear signatures of X-ray reprocessing (reflection) in an accretion disk. Detailed analysis of the highest signal-to-noise spectra with our family of relativistic reflection models RELXILL indicates the presence of both broad and narrow reflection components. We find that a dual-lamppost model provides a superior fit when compared to the standard single lamppost plus distant neutral reflection. In the dual-lamppost model two sources at different heights are placed on the rotational axis of the black hole, suggesting that the narrow component of the Fe K emission is likely to originate in regions far away in the disk, but still significantly affected by its rotational motions. Regardless of the geometry assumed, we find that the inner edge of the accretion disk reaches a few gravitational radii in all our fits, consistent with previous determinations at similar luminosity levels. This confirms a very low degree of disk truncation for this source at luminosities above ~1% Eddington. Our estimates of R_(in) reinforce the suggested behavior for an inner disk that approaches the innermost regions as the luminosity increases in the hard state.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
García, Javier A.0000-0003-3828-2448
Tomsick, John A.0000-0001-5506-9855
Sridhar, Navin0000-0002-5519-9550
Grinberg, Victoria0000-0003-2538-0188
Connors, Riley M. T.0000-0002-8908-759X
Wang, Jingyi0000-0002-1742-2125
Steiner, James F.0000-0002-5872-6061
Dauser, Thomas0000-0003-4583-9048
Walton, Dominic J.0000-0001-5819-3552
Xu, Yanjun0000-0003-2443-3698
Harrison, Fiona A.0000-0003-2992-8024
Foster, Karl0000-0001-5800-5531
Grefenstette, Brian0000-0002-1984-2932
Madsen, Kristin0000-0003-1252-4891
Fabian, Andrew0000-0002-9378-4072
Additional Information:© 2019 The American Astronomical Society. Received 2019 May 4; revised 2019 August 1; accepted 2019 August 2; published 2019 October 29. We thank the anonymous referee for the careful revision of this paper. We also thank Erin Kara and Didier Barret for enlightening discussions on the implications of the dual-lamppost model. J.A.G. acknowledges support from NASA grant NNX17AJ65G and from the Alexander von Humboldt Foundation. R.M.T.C. has been supported by NASA ADAP grant 80NSSC177K0515. V.G. is supported through the Margarete von Wrangell fellowship by the ESF and the Ministry of Science, Research and the Arts Baden-Württemberg. N.S. would like to acknowledge the support from DST-INSPIRE and Caltech SURF-2017 fellowships. 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). Facilities: NuSTAR - The NuSTAR (Nuclear Spectroscopic Telescope Array) mission, Swift. - Software: xspec (v12.10.0c; Arnaud 1996), xillver (García & Kallman 2010; García et al. 2013), relxill (v1.2.0; Dauser et al. 2014; García et al. 2014), nustradas (v1.6.0).
Group:NuSTAR, Space Radiation Laboratory, Astronomy Department
Funding AgencyGrant Number
Alexander von Humboldt FoundationUNSPECIFIED
European Social FundUNSPECIFIED
Baden-Württemberg Ministry of Science, Research and the ArtsUNSPECIFIED
Caltech Summer Undergraduate Research Fellowship (SURF)UNSPECIFIED
Subject Keywords:accretion, accretion disks – atomic processes – black hole physics – line: formation – X-rays: individual (GX 339-4)
Issue or Number:1
Record Number:CaltechAUTHORS:20190809-154849136
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Official Citation:Javier A. García et al 2019 ApJ 885 48
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97736
Deposited By: Tony Diaz
Deposited On:09 Aug 2019 23:07
Last Modified:16 Nov 2021 17:34

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