Related papers: Black-Hole X-Ray Transients: The Effect of Irradia…
Thermal conduction between a cool accretion disk and a hot inner corona can result in either evaporation of the disk or condensation of the hot corona. At low mass accretion rates, evaporation dominates and can completely remove the inner…
The UV emission from X-ray binaries, is more likely to be produced by reprocessing of X-rays by the outer regions of an accretion disk. The structure of the outer disk may be altered due to the presence of X-ray irradiation and we discuss…
We examine in detail several aspects of the physics of accretion disks of possible relevance to the outburst mechanism of the black hole X-ray transients. We adopt the one dimensional, time dependent model described in detail by Cannizzo,…
We have systematically studied the effect of the orbital inclination in the outburst evolution of black hole transients. We have included all the systems observed by the Rossi X-ray timing explorer in which the thermal, accretion disc…
Reflection of X-rays from cool material around a black hole is one of the few observational diagnostics of the accretion flow geometry. Models of this reflected spectrum generally assume that the accretion disk can be characterized by…
In neutron star and black hole X-ray binaries the transitions between the two spectral states, hard and soft, signals the change between accretion via a hot advection-dominated flow(ADAF) and disk accretion. In a few cases the hard/soft…
The X-ray polarimetric observing window re-opening is shedding new light on our current understanding of compact accreting sources. This is true, in particular, for stellar-mass black hole sources observed in the thermally-dominated state,…
The X-ray spectra of accreting stellar-mass black hole systems exhibit spectral features due to reflection, especially broad iron K alpha emission lines. We investigate the reflection by the accretion disc that can be expected in the…
Black hole binary transients undergo dramatic evolution in their X-ray timing and spectral behaviour during outbursts. In recent years a paradigm has arisen in which "soft" X-ray states are associated with an inner disc radius at, or very…
Universal to black hole X-ray binaries, the high-frequency soft lag gets longer during the hard-to-intermediate state transition, evolving from ${\lesssim}1~{\rm ms}$ to ${\sim}10~{\rm ms}$. The soft lag production mechanism is thermal disk…
Recent observations of two black hole candidates (GX 339-4 and J1753.5-0127) in the low-hard state (L_X/L_Edd ~ 0.003-0.05) suggest the presence of a cool accretion disk very close to the innermost stable orbit of the black hole. This runs…
The evolution of an accretion disk, formed as a consequence of the disruption of a star by a black hole, is followed by solving numerically the hydrodynamic equations. The present investigation aims to study the dependence of resulting…
Irradiation of the accretion disc causes reflection signatures in the observed X-ray spectrum, encoding important information about the disc structure and density. A Type I X-ray burst will strongly irradiate the accretion disc and alter…
X-rays are emitted from the corona above the orbiting matter of the accretion disk and travel either directly to us or illuminate the disk. This illumination of the inner disk is enhanced by gravitational light bending, which focuses the…
Accretion around black holes is very often characterized by distinctive X-ray reflection features (mostly, iron inner-shell transitions), which arise due to the primary radiation being reprocessed by a dense and relatively colder medium,…
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…
We review radiative processes responsible for X-ray emission in hard (low) and soft (high) spectral states of black-hole binaries. The main process in the hard state appears to be scattering of blackbody photons from a cold disk by thermal…
We consider the effects of advection and radial gradients of pressure and radial drift velocity on the structure of accretion disks around black holes with proper description of optically thick/thin transitions. We concentrated our efforts…
Galactic black hole (BH) X-ray binaries are known to exhibit episodic outbursts, during which accretion and spectral mode distinctively transition between low/hard and high/soft state. X-ray observations during high/soft state occasionally…
We present angle-dependent, broad-band intensity spectra from accretion disks around black holes of 10 M$_\odot$. In our computations disks are assumed to be slim, which means that the radial advection is taken into account while computing…