Related papers: Expected disk wind properties evolution along an X…
During its 2005 outburst, GRO J1655-40 was observed at high spectral resolution with the Chandra HETGS, revealing a spectrum rich with blueshifted absorption lines indicative of an accretion disk wind -- apparently too hot, too dense, and…
In this paper we study the relation of radio emission to X-ray spectral and variability properties for a large sample of black hole X-ray binary systems. This is done to test, refine and extend -- notably into the timing properties -- the…
We study the outbursts of the black hole X-ray binaries MAXI J1659-152, SWIFT J1753.5--0127 and GX 339-4 with the Swift X-ray Telescope. The bandpass of the X-ray Telescope has access to emission from both components of the accretion flow:…
Highly-ionized fast accretion-disk winds have been suggested as an explanation for a variety of observed absorption and emission features in the X-ray spectra of Active Galactic Nuclei. Simple estimates have suggested that these flows may…
Many astrophysical sources, e.g., cataclysmic variables, X-ray binaries, active galactic nuclei, exhibit a wind outflow, when they reveal a multicolor blackbody spectrum, hence harboring a geometrically thin Keplerian accretion disk. Unlike…
The extent of the accretion disk in the low/hard state of stellar mass black hole X-ray binaries remains an open question. There are some evidence suggesting that the inner accretion disk is truncated and replaced by a hot flow, while the…
We have analyzed {\it Rossi} X-ray timing explorer (RXTE) pointed observations of the outbursts of black hole and neutron star soft X-ray transients in which an initial low/hard state or `island' state, followed by a transition to a softer…
One of the popular models for the low/hard state of Black Hole Binaries is that the standard accretion disk is truncated and the hot inner region produces via Comptonization, the hard X-ray flux. This is supported by the value of the high…
We have carried out detailed analysis on the black hole candidate (BHC) X- ray transient Swift J1753.5-0127 observed by the Rossi X-Ray Timing Explorer (RXTE) during its outburst in 2005 {2006. The spectral analysis shows that the emissions…
In this study, we analysed about $\sim$13 years of publicly available data from MAXI and Swift/BAT to examine the long-term source evolution of 42 transient low-mass X-ray binaries. The sample consists of 11 confirmed black hole X-ray…
We present the results obtained from the spectral studies of black hole X-ray binary GX~339--4 using \astrosat~ observations during its 2021 outburst. \astrosat~ observed the source in the intermediate state for $\sim600$ ks. The combined…
We use simultaneous Swift and RXTE observations of the black hole binary GX 339-4 to measure the inner radius of its accretion disk in the hard state down to 0.4% L_{Edd} via modeling of the thermal disk emission and the relativistically…
It has long been speculated that the nature of the hard X-ray corona may be an important second driver of black hole state transitions, in addition to the mass accretion rate through the disk. However, a clear physical picture of coronal…
The low mass X-ray binary GX 339-4 went into a new outburst in 2021. At the end of the hard to soft transition of this outburst, Insight-HXMT found that the source rapidly alternated between low flux and high flux states on a timescale of…
The three dynamically confirmed wind-fed black hole high-mass X-ray binaries (BH-HMXBs) are suggested to all contain a highly spinning black hole (BH). However, based on the theories of efficient angular momentum transport inside the stars,…
The nature and geometry of the hard state in black hole binaries is controversial. The broadband continuum spectrum and fast variability properties can be explained in a model where the inner disc evaporates into a geometrically thick, hot…
The relative phasing of the X-ray eclipse ephemeris and optical radial velocity (RV) curve for the X-ray binary IC10 X-1 suggests the He[$\lambda$4686] emission-line originates in a shadowed sector of the stellar wind that avoids ionization…
Observational signatures of accretion disc winds have been found in a significant number of low-mass X-ray binaries at either X-ray or optical wavelengths. The 2015 outburst of the black hole transient V404 Cygni provided a unique…
I review the main results from recent 2-D, time-dependent hydrodynamic models of radiation-driven winds from accretion disks in AGN. I also discuss the physical conditions needed for a disk wind to be shielded from the strong X-rays and to…
To understand the evolution of global accretion disk structure in the ``rebrightening'' phase of MAXI J1820$+$070, we perform a comprehensive analysis of its near infrared/optical/UV to X-ray spectral energy distribution (SED) utilizing…