Properties of the 2015 outburst of V404-Cygni from spectral analysis with the TCAF solution
Abstract
Galactic black hole candidate V404-Cygni went through a violent outburst on June 2015 after 26 years of inactivity. Several radio and X-ray flare were observed during the 2015 outburst. We have analyzed rising phase of the outburst using 0.5-150.0 keV Swift/XRT and Swift/BAT data with two component advective flow (TCAF) model fits file in XSPEC. We have also analyzed two NuSTAR data available during our analyzing period. We find that the accretion flow during the outburst was dominated by sub-Keplerian matter. Shock was found to move closer to the black hole as outburst progressed. We did not observe a constant value of normalization, since there were high jet activity. We find the source was in hard state during the initial phase of the outburst. It become softer as outburst progressed but we could not conclude if there is any state transition due to the violent, i.e., rapidly changing accretion nature of the outburst. Spectral state was found softer after radio flare indicating mass ejection from the base of the jet or post-shock region. From the spectral analysis with the TCAF solution, we also obtain mass of the central black hole in the range of 9-12 M_{⊙}.Chakrabarti, S.K., & Titarchuk, L.G., 1995, ApJ, 455, 623Debnath, D., Chakrabarti, S.K., & Mondal, S., 2014, MNRAS, 440, L121Jana, A., Chakrabarti, S. K., & Debnath, D., 2017, ApJ, 850, 91Jana, A., J.-R. Shang, & Debnath, D., et al., 2018 (in preparation)
- Publication:
-
42nd COSPAR Scientific Assembly
- Pub Date:
- July 2018
- Bibcode:
- 2018cosp...42E1597J