Related papers: Advective Disks
When a black hole accretes plasmas at very low accretion rate, an advection-dominated accretion flow (ADAF) is formed. In an ADAF, relativistic electrons emit soft gamma-rays via Bremsstrahlung. Some MeV photons collide with each other to…
We find a new two-temperature hot branch of equilibrium solutions for stationary accretion disks around black holes. In units of Eddington accretion rate defined as $10L_{\rm Edd}/c^2$, the accretion rates to which these solutions…
We develop a new method to describe the accretion flow in the corona above a thin disk around a black hole in vertical and radial extent. The model is based on the same physics as the earlier one-zone model, but now modified including…
Four quiescent elliptical galaxies were imaged with the NRAO VLA at 8.5 GHz. Within the context of canonical advection-dominated accretion flows (ADAFs), these VLA images plus published black hole masses constrain the accretion rates to be…
We study low-density axisymmetric accretion flows onto black holes (BHs) with two-dimensional hydrodynamical simulations, adopting the $\alpha$-viscosity prescription. When the gas angular momentum is low enough to form a rotationally…
When we model black hole accretion sources such as active galactic nuclei and black hole X-ray binaries as advection-dominated accretion flows (ADAFs), it is neccesary to use the global solution to the equations rather than the simpler…
We present global solutions of optically thin, two-temperature black hole accretion disks incorporating magnetic fields. We assume that the {\pi}{\phi}-component of the Maxwell stress is proportional to the total pressure, and prescribe the…
We report on a new class of solutions of black hole accretion disks that we have found through three-dimensional, global, radiative magnetohydrodynamic simulations in general relativity. It combines features of the canonical thin, slim and…
We numerically construct slim, global, vertically integrated models of optically thin, transonic accretion discs around black holes, assuming a regularity condition at the sonic radius and boundary conditions at the outer radius of the disc…
Aims: The hard and soft spectral states of black hole accretion are understood as connected with ADAF accretion (truncated disk) and standard disk accretion, respectively. However, observations indicate the existence of cool gas in the…
Convection-dominated accretion flows (CDAF) are expected to have a shallower density profile and a higher radiation efficiency as compared to advection-dominated accretion flows (ADAF). Both solutions have been developed to account for the…
Using the H$\beta$ linewidth, we obtained the virial central supermassive black hole masses and then the Eddington ratios in a sample of broad-line AGNs and NLS1s observed by ASCA. Combined with the data from ROSAT and Chandra observations,…
Jets and outflows are known to form out of advective accretion flows around black holes. Hard photons from the centrifugal barrier directly hit the electrons and deposit momentum on them. For optically thick flows such deposition is not…
We calculate the advection/diffusion of the large-scale magnetic field threading an ADAF, and find that the magnetic field can be dragged inward by the accretion flow efficiently, if the magnetic Prandtl number P~1. This is due to the large…
Advection-dominated accretion flows (ADAFs) are known to be convectively unstable for low values of the viscosity parameter alpha. Two-dimensional axisymmetric hydrodynamic simulations of such flows reveal a radial density profile which is…
We review models which include advective accretion disks onto compact objects and discuss the influence of the centrifugal pressure supported high density region close to the compact objects on the emitted spectra. We show that the…
We investigate the model of the disc/corona accretion flow around the black hole. The model, parameterized by the total (i.e. disk plus corona) accretion rate, $\dot m$, mass of the black hole, $M$ and the viscosity parameter, $\alpha$,…
We consider the effects of advection and radial gradients of pressure and radial drift velocity on the structure of accretion disks around black holes with proper description of optically thick/thin transitions. We concentrated our efforts…
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…
Adopting the advection dominated accretion flow (ADAF) model, we have re-examined the radiation emitted by isolated stellar-mass black holes accreting from the interstellar medium of our Galaxy. Two distinct types of black holes are given…