The X-ray Spectral Analysis of V404 Cygni Outburst in 2015 with the Tcaf Model
Jie-Rou Shang1*, Hsiang-Kuang Chang1,2, Dipak Debnath3
1Institute of Astrophysics, National Tsing Hua University, Hsinchu, Taiwan
2Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
3Indian Centre For Space Physics, Kolkata, India
* presenting author:Jie-Rou Shang,
V404 Cygni (GS 2023+338) is a galactic X-ray binary containing a black hole candidate. It is an X-ray transient exhibiting 3 outbursts in the 1980’s. After a long period of quiescence, V404 Cygni had an outburst again in 2015 June. This outburst lasted for about one month in soft X-rays. Meanwhile, multi-wavelength observations of this outburst from radio to gamma-rays were conducted.

We apply the Two-Component Advective Flow (TCAF) model to this outburst to understand its physical properties. The TCAF model, developed by Chakrabarti et al. (1995), considers the disc accretion rate (Keplerian, high angular momentum) and the halo accretion rate (sub-Keplerian, low angular momentum) as soft and hard components to explain spectral properties. Relevant parameters can also describe QPO phenomena produced by the Compton cloud around the central black hole.

We will introduce the TCAF model and report the estimated mass of the black hole in V404 Cygni based on TCAF spectral fitting of data taken by Swift/XRT from 15 June to 8 July 2015.

Keywords: X-ray binary, black hole