Spectral and Temporal Analysis of the Supergiant Fast X-ray Transient IGR J16195–4945 with SRG/ART-XC

Abstract

We present the results of the analysis of the SRG/ART-XC observation of the Supergiant Fast X-ray Transient IGR J16195-4545 performed on March 3, 2021. Six bright flares are present in the light curve, with no significant change in hardness occuring during these flares. The spectrum is described with an absorbed power law model with a high energy exponential cutoff showing heavy absorption, with \(N_{\textrm{H}}=(12\pm 2)\times 10^{22}\text{ cm}^{-2}\) and \(\Gamma=0.56\pm 0.15\), \(E_{\textrm{cut}}=13\pm 2\) keV. Adopting the Bayesian block decomposition of the light curve, we measured the properties of the observed flares (duration, rise time, waiting time, released energy and pre-flare luminosity), which are consistent with the quasi-spherical subsonic accretion model. The stellar wind velocity of the supergiant is estimated to be \(v_{w}\approx 500\) km s\({}^{-1}\). Additionally, the system was found to have an unusual near-IR variability.