Related papers: Accretion geometry of the black hole binary MAXI J…
The evolution of the inner accretion flow of a black hole X-ray binary (BHXRB) during the outburst is still a matter of active research. X-ray reverberation lags are powerful tools to constrain the disk-corona geometry. We present a study…
Black hole X-ray binaries undergo occasional outbursts caused by changing inner accretion flows. Here we report high-angular resolution radio observations of the 2013 outburst of the black hole candidate X-ray binary system J1908+094, using…
We extract the spectra of the fastest variability (above 10 Hz) from the black hole XTE J1550-564 during a transition from hard to soft state on the rise to outburst. We confirm previous results that the rapid variability contains no…
We address the ability of broad iron emission lines from black hole accretion disks to diagnose the spin of the black hole. Using a high-resolution 3-dimensional MHD simulation of a geometrically-thin accretion disk in a Pseudo-Newtonian…
We present the results of a new global radiation transport code coupled to a general relativistic magneto-hydrodynamic simulation of an accreting, non-rotating black hole. For the first time, we are able to explain from first principles in…
MAXI J1305-704 has been proposed as a high-inclination candidate black hole X-ray binary in view of its X-ray properties and dipping behaviour during outburst. We present photometric and spectroscopic observations of the source in…
Accreting stellar-mass black holes often show a `Type-C' quasi-periodic oscillation (QPO) in their X-ray flux, and an iron emission line in their X-ray spectrum. The iron line is generated through continuum photons reflecting off the…
We present a spectroscopic analysis of XRISM and NuSTAR observations of the black hole X-ray binary GS~1354--64 during its 2026 outburst. A total number of 3.5 million photons are collected by the microcalorimeter Resolve on board XRISM,…
Using the flux resolved spectroscopy for the first time, we analyse the RXTE/PCA data of the black hole X-ray binaries GRS 1915+105 and IGR J17091-3624, when both sources show large amplitude, quasi-regular oscillations in 2.0-60.0 keV…
We present the results obtained from detailed timing and spectral studies of a black hole candidate MAXI~J1813-095 using {\it Swift}, {\it NICER}, and {\it NuSTAR} observations during its 2018 outburst. The timing behaviour of the source is…
Recent X-ray observations have shown evidence for exceptionally broad and skewed iron K alpha emission lines from several accreting black hole systems. The lines are assumed to be due to fluorescence of the accretion disk illuminated by a…
We report on the results of optical, near-infrared (NIR) and mid-infrared observations of the black hole X-ray binary candidate (BHB) MAXI J1535-571 during its 2017/2018 outburst. During the first part of the outburst (MJD 58004-58012), the…
Two component X-ray spectra (soft multicolor black body plus harder power law) are frequently observed from accreting black holes. These components are presumably associated with the different parts of the accretion flow (optically thick…
In this review, I summarize the main X-ray/hard X-ray properties of the accretion flows around black holes and neutron stars based on recent broad-band spectral and timing observations performed by the BeppoSAX and Rossi X-ray Timing…
The observed spectra from black hole (BH) X-ray binaries (XRBs) typically consist of two primary components: multitemperature blackbody (BB) originating from the accretion disk in soft X-ray, and a power-law like component in hard X-ray due…
The broad X-ray iron line seen in the spectra of many AGN is thought to originate from the inner regions of the putative black hole accretion disk, and hence provides a rare probe of that central region. In principle, future high throughput…
MAXI J1348-630 is a low mass X-ray binary discovered in 2019 during a bright outburst. During this event, the system sampled both hard and soft states following the standard evolution. We present multi-epoch optical and near-infrared…
A major question in the study of black hole binaries involves our understanding of the accretion geometry when the sources are in the hard state. In this state, the X-ray energy spectrum is dominated by a hard power-law component and radio…
The power spectrum of the X-ray fluctuations of accreting black holes often consists of two broad humps. We quantitatively investigate the hypothesis that the lower frequency hump orig- inates from variability in a truncated thin accretion…
We have analyzed archival Ginga data of a number of Soft X-ray Transient sources and modelled them in an attempt to constrain the geometry and physical properties of accretion. Our models include a self-consistent description of X-ray…