2023-03-17 Abstract

Title:  Black Hole X-ray Binaries: Global Understanding via Spectro-Temporal Analysis
Speaker:  Dipak Debnath
Date: March 17 at 14:30
Location: R521, General Building II
Stellar Massive Black Hole X-ray Binaries (BHXRBs) are very interesting as they show rapid variation in their spectral and timing properties. BHXRBs are generally two types: persistent and transient. Transient BHXRBs stay most of their lifetime in a low luminosity quiescent phase. They become occasionally active and show single or
multi-peaked outbursts. The nature of these outbursts in terms of the duration, the number of peaks, maximum peak intensity, and so on varies. Recently, we have studied three well-known recurring transient BHXRBs: H 1743-322, GX 339-4, 4U 1630-472 using archival data of RXTE/ASM and MAXI/GSC for around two and half decades. Studying these sources, we have made an effort to understand the triggering mechanism of outbursts, their relation with the quiescent phases, etc. We also
tried to find a physical reason behind the complete (when four defined spectral states, such as hard, hard-intermediate, soft-intermediate and soft are observed) or failed outbursts. In a failed outburst, we generally do not see the presence of the soft state, sometimes even intermediate states are also found to be missing. So, our study of three recurrent transient BHXRBs sheds light on long-term accretion dynamics in outbursting sources. The combined detailed study of the spectral and temporal properties of the transient black hole candidates (BHC) with physical models allow us to understand accretion flow dynamics during their active phases. We can also estimate intrinsic source parameters from our study.