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Characterizing X-ray and Radio emission in the Black Hole X-Ray Binary V404 Cygni during Quiescence

Rana, Vikram and Loh, Alan and Corbel, Stéphane and Tomsick, John A. and Chakrabarty, Deepto and Walton, Dominic J. and Barret, Didier and Boggs, Steven E. and Christensen, Finn E. and Craig, William and Fuerst, Felix and Gandhi, Poshak and Grefenstette, Brian W. and Hailey, Charles and Harrison, Fiona A. and Madsen, Kristin K. and Rahoui, Farid and Stern, Daniel and Tendulkar, Shriharsh P. and Zhang, William W. (2016) Characterizing X-ray and Radio emission in the Black Hole X-Ray Binary V404 Cygni during Quiescence. Astrophysical Journal, 821 (2). Art. No. 103. ISSN 0004-637X. doi:10.3847/0004-637X/821/2/103.

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We present results from multi-wavelength simultaneous X-ray and radio observations of the black hole X-ray binary V404 Cyg in quiescence. Our coverage with NuSTAR provides the very first opportunity to study the X-ray spectrum of V404 Cyg at energies above 10 keV. The unabsorbed broadband (0.3–30 keV) quiescent luminosity of the source is 8.9 × 10^(32) erg s^(−1) for a distance of 2.4 kpc. The source shows clear variability on short timescales (an hour to a couple of hours) in the radio, soft X-ray, and hard X-ray bands in the form of multiple flares. The broadband X-ray spectra obtained from XMM-Newton and NuSTAR can be characterized with a power-law model having a photon index of Γ = 2.12 ± 0.07 (90% confidence errors); however, residuals at high energies indicate spectral curvature significant at a 3σ confidence level with the e-folding energy of the cutoff as 20_(-7)^(+20) keV. Such curvature can be explained using synchrotron emission from the base of a jet outflow. Radio observations using the VLA reveal that the spectral index evolves on very fast timescales (as short as 10 minutes), switching between optically thick and thin synchrotron emission, possibly due to instabilities in the compact jet or stochastic instabilities in the accretion rate. We explore different scenarios to explain this very fast variability.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Rana, Vikram0000-0003-1703-8796
Tomsick, John A.0000-0001-5506-9855
Chakrabarty, Deepto0000-0001-8804-8946
Walton, Dominic J.0000-0001-5819-3552
Barret, Didier0000-0002-0393-9190
Boggs, Steven E.0000-0001-9567-4224
Christensen, Finn E.0000-0001-5679-1946
Fuerst, Felix0000-0003-0388-0560
Gandhi, Poshak0000-0003-3105-2615
Grefenstette, Brian W.0000-0002-1984-2932
Harrison, Fiona A.0000-0003-2992-8024
Madsen, Kristin K.0000-0003-1252-4891
Rahoui, Farid0000-0001-7655-4120
Stern, Daniel0000-0003-2686-9241
Tendulkar, Shriharsh P.0000-0003-2548-2926
Zhang, William W.0000-0002-1426-9698
Additional Information:© 2016 The American Astronomical Society. Received 2015 July 14; accepted 2016 February 10; published 2016 April 19. We thank Michael A. Nowak for useful discussion on synchrotron model. 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 NASA. We thank the NuSTAR Operation, 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). SC would like to thank James Miller-Jones for excellent help during the preparation of the JVLA observations. SC and AJ acknowledges the financial support from the UnivEarthS Labex programme of Sorbonne Paris Cit´e (ANR-10-LABX-0023 and ANR-11-IDEX-0005-02), and from the CHAOS project ANR-12-BS05-0009 supported by the French Research National Agency. JAT acknowledges partial support from NASA under XMM-Newton Guest Observer grant NNX14AF08G. Facilities: NuSTAR, XMM-Newton, JVLA.
Group:NuSTAR, Space Radiation Laboratory
Funding AgencyGrant Number
Agence Nationale pour la Recherche (ANR)ANR-10-LABX-0023
Agence Nationale pour la Recherche (ANR)ANR-11-IDEX-0005-02
Agence Nationale pour la Recherche (ANR)ANR-12-BS05-0009
Subject Keywords:accretion, accretion disks; stars: black holes; stars: individual (V404 Cyg) ; X-rays: binaries
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2016-58
Issue or Number:2
Record Number:CaltechAUTHORS:20150801-085134688
Persistent URL:
Official Citation:Vikram Rana et al 2016 ApJ 821 103
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59134
Deposited By: Joy Painter
Deposited On:06 Aug 2015 17:40
Last Modified:10 Nov 2021 22:15

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