Mass-losing accretion discs around supermassive black holes

Accretion Discs around Black Holes: Developement of Theory

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 connected with nonlinear hydrodynamic instability, convection, and magnetic field. In standard theory there are two branches of solution, optically thick, and ...

Growing Supermassive Black Holes by Chaotic Accretion

We consider the problem of growing the largest supermassive black holes from stellar–mass seeds at high redshift. Rapid growth without violating the Eddington limit requires that most mass is gained while the hole has a low spin and thus a low radiative accretion efficiency. If, as was formerly thought, the black–hole spin aligns very rapidly with the accretion flow, even a randomly–oriented se...

Dark Matter Accretion into Supermassive Black Holes

Aligning spinning black holes and accretion discs

We consider the alignment torque between a spinning black hole and an accretion disc whose angular momenta are misaligned. This situation must hold initially in almost all gas accretion events on to supermassive black holes, and may occur in binaries where the black hole receives a natal supernova kick. We show that the torque always acts to align the hole’s spin with the total angular momentum...

Accretion flows around stellar mass black holes and neutron stars

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 Explorer satellites. Emphasizing the spectral and timing similarities observed between black holes and neutron stars, I discuss on the most likely accretion geomet...