Related papers: Radiatively driven electron-positron jets from two…
Black hole and neutron star accretion flows display unusually high levels of hard coronal emission in comparison to all other optically thick, gravitationally bound, turbulent astrophysical systems. Since these flows sit in deep…
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…
Disk accretion may be the fundamental astrophysical process. Stars and planets form through the accretion of gas in a disk. Black holes and galaxies co-evolve through efficient disk accretion onto the central supermassive black hole.…
We present spectral properties of an accretion disk model, in which a Keplerian accretion disk is flanked by a sub-Keplerian halo component terminating at a standing shock. The post-shock region (which may be considered to be the boundary…
We study nucleosynthesis in low accretion rate hot advective flows around black holes. We find that matter is generally photo-dissociated into protons and neutrons inside the disk. These neutrons stay around black holes for longer time…
We study the efficiency of radiation in driving jets around black holes. Including general relativity for the radiation driving, we also show that the radiation field is affected by strong gravitational field in non linear manner, making…
Close to a black hole, the density of the sub-Keplerian accreting matter becomes higher compared to a spherical flow due to the presence of a centrifugal barrier independent of whether or not a standing shock actually forms. This hot dense…
Using long-duration general relativistic magnetohydrodynamic simulations of radiatively inefficient accretion discs, the energy, momentum and mass outflow rates from such systems are estimated. Outflows occur via two fairly distinct modes:…
A black hole accretion may have both the Keplerian and the sub-Keplerian component. In the so-called Chakrabarti-Titarchuk scenario, the Keplerian component supplies low energy (soft) photons while the sub-Keplerian component supplies hot…
We carry out a general relativistic study of radiatively driven, conical fluid jets around non-rotating black holes and investigate the effects and significance of radiative acceleration, as well as radiation drag. We apply relativistic…
Rotating accretion flow may undergo centrifugal pressure mediated shock transition even in presence of various dissipative processes, such as viscosity and cooling mechanism. The extra thermal gradient force along the vertical direction in…
The collapse of young massive stars or the coalescence of a black hole-neutron star binary is expected to give rise to a black hole-torus system. When the torus is strongly magnetized, the black hole produces electron-positron outflow along…
An ejection mechanism of relativistic jets from slim disks is studied. Since the radiation pressure is dominant in the slim disk, radiative energy flow arises along the pressure gradient in the vertical direction. The divergence of the…
We present an analytic description of turbulent, MHD disk accretion around black holes that specifically addresses the relationship between radial and vertical, transport, thereby complementing and extending numerical simulations. The…
The quasi-steady structure of super-critical accretion flows around a black hole is studied based on the two-dimensional radiation-hydrodynamical (2D-RHD) simulations. The super-critical flow is composed of two parts: the disk region and…
We analyse flows around a rotating black hole and obtain self-consistent accretion-ejection solutions in full general relativistic prescription. Entire energy-angular momentum parameter space is investigated in the advective regime to…
We consider photon emission from a supercritical accretion disk in which photons in the inner regions are trapped and advected in towards the center. Such disks are believed to be present in failed supernovae and gamma-ray bursts, and…
We present time-dependent simulations of a two-phase accretion flow around a black hole. The accretion flow initially is composed of an optically thick and cool disc close to the midplane, while on top and below the disc there is a hot and…
We use moment formalism of relativistic radiation hydrodynamics to obtain equations of motion of radial jets and solve them using polytropic equation of state of the relativistic gas. We consider curved space-time around black holes and…
Most of the luminosity of accreting black hole is emitted in the X-ray band. This radiation is believed to emerge, through inverse Compton process, from a hot (Te ~ 10^8 -10^9 K) optically thin (Thomson optical depth ~ 1) plasma probably…