相关论文: Implementation of Two Component Advective Flow Sol…
We investigate the global structure of the advection dominated accretion flow around a Schwarzschild black hole where the accretion disc is threaded by toroidal magnetic fields. We consider synchrotron radiative process as an effective…
Using a generalized non-spherical, multi-transonic accretion flow model, we analytically calculate the normalized QPO frequency ${\bar {\bf {\nu}}}_{qpo}$ of galactic black hole candidates in terms of dynamical flow variables and…
We present a survey of how the spectral features of black hole X-ray binary systems depend on spin, accretion rate, viewing angle, and Fe abundance when predicted on the basis of first principles physical calculations. The power law…
We investigate the behaviour of low angular momentum viscous accretion flows around black holes using Smooth Particle Hydrodynamics (SPH) method. Earlier, it has been observed that in a significant part of the energy and angular momentum…
General relativistic, axisymmetric flow of low angular momentum accretion around a Kerr black hole can have certain geometric configuration where the flow is maintained in hydrostatic equilibrium along the vertical direction (direction…
Field-channelled accretion flows occur in a variety of astrophysical objects, including T Tauri stars,magnetic cataclysmic variables and X-ray pulsars. We consider a curvilinear coordinate system and derive a general hydrodynamic…
Astronomers have discovered many potential black holes in X-ray binaries and galactic nuclei. These black holes are usually identified by the fact that they are too massive to be neutron stars. Until recently, however, there was no…
Astronomers have discovered many potential black holes in X-ray binaries and galactic nuclei. These black holes are usually identified by the fact that they are too massive to be neutron stars. Until recently, however, there was no…
We present the results from axisymmetric time-dependent HD calculations of gas flows which are under the influence of gravity of a black hole in quasars. We assume that the flows are non-rotating and exposed to quasar radiation. We take…
We present the global solutions of low angular momentum, inviscid, advective accretion flow around Kerr-Taub-NUT (KTN) black hole in presence and absence of shock waves. These solutions are obtained by solving the governing equations that…
An accreting system in two-temperature regime, admits multiple solutions for the same set of constants of motion, producing widely different spectra. Comparing observed spectrum with that derived from a randomly chosen accretion solution,…
Low angular momentum accretion flows very often have centrifugal pressure supported standing shock waves which can accelerate flow particles. The accelerated particles in turn emit synchrotron radiation in presence of magnetic fields.…
I provide a broad overview of the basic theoretical paradigms of black hole accretion flows. Models that make contact with observations continue to be mostly based on the four decade old alpha stress prescription of Shakura & Sunyaev…
We study the spectral properties of a very general class of accretion disks which can be decomposed into three distinct components apart from a shock at $r=r_s$: (1) An optically thick Keplerian disk on the equatorial plane ($r>r_s$), (2) A…
We consider time-dependent models for rotating accretion flows onto black holes, where a transition takes place from an outer cooling-dominated disc to a radiatively inefficient flow in the inner region. In order to allow for a transition…
We study viscous accretion disc around black holes, and all possible accretion solutions, including shocked as well as shock free accretion branches. Shock driven bipolar outflows from a viscous accretion disc around a black hole has been…
We study the time evolution of a rotating, axisymmetric, viscous accretion flow around black holes using a grid based finite difference method. We use the Shakura-Sunyaev viscosity prescription. However, we compare with the results obtained…
We examine the effect of thermal conduction on the low-angular momentum hot accretion flow (HAF) around non-rotating black holes accreting mass at very low rate. While doing so, we adopt the conductive heat flux in the saturated form, and…
The Galactic transient black hole candidate GX 339-4 is a very interesting object to study as it showed both complete and failed types of outbursts. We studied both spectral and temporal properties of the 2017-18 outburst of the source…
Simulations of hot, pressure supported, tilted black hole accretion flows, in which the angular momentum of the flow is misaligned with the black hole spin axis, can exhibit two non-axisymmetric shock structures in the inner regions of the…