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

Vikram Rana; Alan Loh; Stéphane Corbel; John A. Tomsick; Deepto Chakrabarty; Dominic J. Walton; Didier Barret; Steven E. Boggs; Finn E. Christensen; William Craig; Felix Fuerst; Poshak Gandhi; Brian W. Grefenstette; Charles Hailey; Fiona A. Harrison; Kristin K. Madsen; Farid Rahoui; Daniel Stern; Shriharsh Tendulkar; William W. Zhang

doi:10.3847/0004-637X/821/2/103

Journal articles

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

Vikram Rana ¹ Alan Loh ² Stéphane Corbel ³ John A. Tomsick ⁴ Deepto Chakrabarty ⁵ Dominic J. Walton ¹ Didier Barret ⁶ Steven E. Boggs ⁴ Finn E. Christensen ⁷ William Craig ^{8, 4} Felix Fuerst ¹ Poshak Gandhi ⁹ Brian W. Grefenstette ¹ Charles Hailey ¹⁰ Fiona A. Harrison ¹ Kristin K. Madsen ¹ Farid Rahoui ¹¹ Daniel Stern ¹⁰ Shriharsh Tendulkar ¹ William W. Zhang ¹²

1 Cahill Center for Astronomy and Astrophysics

2 AIM (UMR_7158 / UMR_E_9005 / UM_112) - Astrophysique Interprétation Modélisation

3 USN - Unité Scientifique de la Station de Nançay

4 SSL - Space Sciences Laboratory [Berkeley]

5 MIT Kavli Institute for Astrophysics and Space Research

6 IRAP - Institut de recherche en astrophysique et planétologie

7 DTU - Technical University of Denmark [Lyngby]

8 LLNL - Lawrence Livermore National Laboratory

9 Department of Physics, Durham University

10 JPL - Jet Propulsion Laboratory

11 ESO - European Southern Observatory

12 GSFC - NASA Goddard Space Flight Center

Abstract : 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 broad-band (0.3--30 keV) quiescent luminosity of the source is 8.9$\times$10$^{32}$ erg s$^{-1}$ for a distance of 2.4 kpc. The source shows clear variability on short time scales (an hour to a couple of hours) in radio, soft X-ray and hard X-ray bands in the form of multiple flares. The broad-band X-ray spectra obtained from XMM-Newton and NuSTAR can be characterized with a power-law model having photon index $\Gamma$=2.12$\pm$0.07 (90\% confidence errors); however, residuals at high energies indicate spectral curvature significant at a 3$\sigma$ confidence level with e-folding energy of the cutoff to be 20$^{+20}_{-7}$ 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 time-scales (as short as 10 min.), switching between optically thick and thin synchrotron emission, possibly due to instabilities in the compact jet or stochastic instabilities in accretion rate. We explore different scenarios to explain this very fast variability.

Keywords : black hole X-ray binaries: general low mass X-ray binary: i ndividual (V404 Cygni)

Document type :

Journal articles

Domain :

Sciences of the Universe [physics] / Astrophysics [astro-ph]

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https://hal-insu.archives-ouvertes.fr/insu-01369644
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Submitted on : Tuesday, March 21, 2017 - 2:09:19 PM
Last modification on : Tuesday, October 12, 2021 - 5:20:20 PM
Long-term archiving on: : Thursday, June 22, 2017 - 1:02:04 PM

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

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

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