Related papers: On the Particle Heating and Acceleration in Black …
Plasmas in an accretion flow are heated by MHD turbulence generated through the magneto-rotational instability. The viscous stress driving the accretion is intimately connected to the microscopic processes of turbulence dissipation. We show…
Two related topics are discussed. 1. Accretion onto black holes at low and high (though not very high) rates is believed to proceed adiabatically ({\em ie} non-radiatively). It is argued that the liberated energy is carried off by an…
We calculate the amount of angular momentum that thermal photons carry out of a viscous black hole accretion disc, due to the strong Doppler shift imparted to them by the high orbital velocity of the radiating disc material. While the…
The radial transport of angular momentum in accretion disk is a fundamental process in the universe. It governs the dynamical evolution of accretion disks and has implications for various issues ranging from the formation of planets to the…
These lectures provide an overview of the theory of accretion disks with application to bright sources containing black holes. I focus on the fundamental physics of these flows, stressing modern developments and outstanding questions…
We describe the most general nature of accretion and wind flows around a compact object and emphasize on the properties which are special to black hole accretion. The angular momentum distribution in the most general solution is far from…
Observations over the past decade have verified, beyond reasonable doubt, that most galactic nuclei contain massive black holes. Hole masses are being measured and firm evidence for spin is being sought. Attention is now returning to the…
I outline the theory of accretion onto black holes, and its application to observed phenomena such as X-ray binaries, active galactic nuclei, tidal disruption events, and gamma-ray bursts. The dynamics as well as radiative signatures of…
We describe astrophysical processes around a black hole keeping primarily the physics of accretion in mind. In Section 1, we briefly discuss the formation, evolution and detection of black holes. We also discuss the difference of flow…
The accretion flow in the disk dominated state of black hole binaries has peak temperature and luminosity which vary together in such a way as to indicate an approximately constant emitting area. The association of this with the last stable…
A solid theoretical understanding of how inflowing, accreting plasma around black holes and other compact objects gives rise to outflowing winds and jets is still lacking, despite decades of observations. The fact that similar processes and…
We study the spin dependence of accretion onto rotating Kerr black holes using analytic techniques. In its linear regime, angular momentum transport in MHD turbulent accretion flow involves the generation of radial magnetic field connecting…
We consider accretion of charged test matter by rotating, magnetic black holes and discuss a number of aspects in which the interaction of the angular momentum contained in the electromagnetic field and the spin of the hole plays a…
An accretion flow onto a supermassive black hole is the primary process powering quasars. However, a geometry of this flow is not well constrained. Both global MHD simulations and observations suggest that there are several emission…
The principles underlying a proposed class of black hole accretion models are examined. The flows are generally referred to as ``convection-dominated,'' and are characterized by inward transport of angular momentum by thermal convection and…
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 briefly review recent developments in black hole accretion disk theory, emphasizing the vital role played by magnetohydrodynamic (MHD) stresses in transporting angular momentum. The apparent universality of accretion-related outflow…
We explore the effects of anisotropic thermal conduction, anisotropic pressure, and magnetic field strength on the hot accretion flows around black holes by solving the axisymmetric, steady-state magnetohydrodynamic equations. The…
Standard accretion disk theory is formulated which is based on the local heat balance. The energy produced by a turbulent viscous heating is supposed to be emitted to the sides of the disc. Sources of turbulence in the accretion disc are…
We briefly review recent developments in black hole accretion disk theory, placing new emphasis on the vital role played by magnetohydrodynamic (MHD) stresses in transporting angular momentum. The apparent universality of accretion-related…