Related papers: Angular momentum transport by thermal emission in …
A key component of explaining the array of galaxies observed in the Universe is the feedback of active galactic nuclei, each powered by a massive black hole's accretion disc. For accretion to occur, angular momentum must be lost by that…
The lack of our knowledge on how angular momentum is transported in accretion disks around black holes has prevented us from fully understanding their high energy emissions. We briefly highlight some theoretical models, emphasizing the…
If a Kerr black hole is connected to a disk rotating around it by a magnetic field, the rotational energy of the Kerr black hole provides an energy source for the radiation of the disk in addition to disk accretion. The black hole exerts a…
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…
The influence of disc radiation capture upon black hole rotational evolution is negligible for radiatively inefficient discs. For the standard thin disc model it is a slight but potentially important effect leading to the equilibrium spin…
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…
The mechanism of angular momentum transport in accretion discs has long been debated. Although the magnetorotational instability appears to be a promising process, poorly ionized regions of accretion discs may not undergo this instability.…
We study the ejection of winds from thin accretion discs around stellar mass black holes and the time evolution of these winds in presence of radiation field generated by the accretion disc. Winds are produced by radiation, thermal pressure…
We present a model for the transport of anisotropic turbulence in an accretion disc. The model uses the Reynolds stress tensor approach in the mean field approximation. To study the role of convection in a protoplanetary disc, we combine…
We show that the removal of angular momentum is possible in the presence of large scale magnetic stresses in geometrically thick, advective, sub-Keplerian accretion flows around black holes in steady-state, in the complete absence of…
In this paper, we consider angular momentum fluctuations of a Schwartzschild black hole in thermal equilibrium with radiation which, for the sake of simplicity is here modeled by a scalar field. Important, we do not set the black hole…
Thermal emission from the accretion disc around a black hole can be polarized, due to Thomson scattering in a disc atmosphere. In Newtonian space, the polarization angle must be either parallel or perpendicular to the projection of the disc…
Disc accretion on to a black hole is often misaligned from its spin axis. If the disc maintains a significant magnetic field normal to its local plane, we show that dipole radiation from Lense-Thirring precessing disc annuli can extract a…
We show that the removal of angular momentum is possible in the presence of large scale magnetic stresses, arisen by fields much stronger than that required for magnetorotational instability, in geometrically thick, advective, sub-Keplerian…
Accretion disks around black holes radiate a significant fraction of the rest mass of the accreting material in the form of thermal radiation from within a few gravitational radii of the black hole ($ r \lesssim 20 G M / c^{2}$). In…
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…
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…
(Abridged) We study the dynamical evolution of a stationary, axisymmetric, and perfectly conducting cold accretion disk containing a large-scale magnetic field around a Kerr black hole, trying to understand the relation between accretion…
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…
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…