Conveners
Black Hole: Observations: Session 1
- Anuj Nandi (U R Rao Satellite Centre, Bengaluru)
Black Hole: Observations: Session 2
- Ranjeev Misra (IUCAA, Pune)
The study of X-ray binaries in the outbursting phase is crucial to understand the accretion process and the underlying physics. Every outburst is different regarding energy budget and the observed spectral-timing properties. In this presentation, I will summarise the lesson learned from the study of these systems. Also, I will discuss
some of the key issues in this topic based on our recent studies.
Extragalactic Black Hole X-ray Binaries (BH-XRBs) are the most intriguing X-ray sources as some of these systems are ‘home’ to the most massive stellar mass BHs ever found. Most of these sources accrete matter through a stellar wind, making them ideal for studying the dynamics of accretion disks in massive binary systems. In this work, we study the X-ray properties of three massive (MBH =...
Masses of most black holes discovered in X-ray binaries lie within a narrow range of 5 - 20 M$_\odot$. The formation of these black holes is understood using scenarios involving collapse of massive stars. Contrary to X-ray binaries, black holes discovered using gravitational waves from merger events have masses going up to 200 M$_\odot$. This apparent dichotomy had given rise to a belief of...
Studying the nature of type-B/C QPOs in different scenarios can decipher their production mechanism. We have analyzed the appearance or disappearance of type-B ~4.5 Hz and type-C ~9.5 Hz QPOs of BH source H1743-322 and found no change in the disk inner radius but power-law indices are varying. Quasi-simultaneous radio observations indicate that either a corona or a jet is responsible for the...
The Galactic BHC MAXI J1348-630 was discovered by MAXI/GSC and Swift/BAT satellites in 2019. The source had undergone two major outbursts in 2019, shortly after its discovery. Using archival data from multiple satellites (including Swift, MAXI, NICER, NuSTAR, and AstroSat) we have performed a detailed spectral and temporal analysis of both the outbursts. The first outburst lasted for four...
Cygnus X-1 is a well-known galactic accreting black hole binary that shows several observational features suggesting a complex interaction between the accretion disk, its atmosphere called Corona, and the jet. The polarisation characteristics of the Corona and the jet are different. To understand the high energy emission mechanism and the system's geometry, we have carried out a...
We present broadband X-ray spectral and timing analysis of the black hole X-ray binary MAXI J1348–630, performed using five AstroSat observations. The source was in the soft spectral state for the first three observations and in the hard state for the last two. The power density spectra are substantially weak in the soft state compared to the hard state. In addition, we detected quasi-periodic...
We present the results from X-ray broadband spectro-temporal analyses of recurrent outbursting sources GX 339$-$4 and H 1743$-$322 using AstroSat and NuSTAR archival observations carried out during $2016-2022$. GX 339$-$4 was found to be making transition from quiescence to outburst, and the wide-band spectral analyses results during outbursts shows that GX 339$-$4 was in hard ($kT_{\rm...
The enigmatic black hole X-ray binary GRS1915+105 exhibits diverse variability patterns (i.e., θ, β, δ, ρ, κ, ω, and γ classes) as observed with AstroSat. We present a generic feature of time-lag properties for the HFQPO observations which belong to the δ, ω, κ and γ variability class. For the first time, we detect soft-lag associated with the 67 Hz HFQPO for all four variability classes of...
We study the recent outburst of the black hole candidate EXO 1846-031 which went into an outburst in 2019 after almost 34 years in quiescence. We use archival data from Swift/XRT, MAXI/GSC, NICER/XTI and NuSTAR/FPMA satellites/instruments to study the evolution of the spectral and temporal properties of the source during the initial rising phase of the outburst. Evolving type-C quasi-periodic...
4U 1543-47 is a galactic low-mass X-ray binary discovered in 1971. It has undergone five outbursts. The fifth outburst that happened in 2021 marks the source as the brightest X-ray binary source ever reported with a peak X-ray intensity of $\sim$11 Crab in 2-4 keV with MAXI/GSC. We aim for a comprehensive analysis of the wideband spectral characteristics of the source using NICER, NuSTAR...
