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We describe new optically thin solutions for rotating accretion flows around black holes and neutron stars. These solutions are advection dominated, so that most of the viscously dissipated energy is advected radially with the flow. We…

Astrophysics · Physics 2009-10-22 Ramesh Narayan , Insu Yi

We present global solutions that describe advection-dominated accretion flows around black holes. The solutions are obtained by numerically solving a set of coupled ordinary differential equations corresponding to a steady axisymmetric…

Astrophysics · Physics 2009-10-28 Ramesh Narayan , Shoji Kato , Fumio Honma

We describe hot, optically-thin solutions for one-temperature accretion disks around black holes. We include cooling by synchrotron, bremsstrahlung, and Comptonization. Our solutions are thermally and viscously stable, with gas temperatures…

Astrophysics · Physics 2016-08-30 A. A. Esin , R. Narayan , E. Ostriker , I. Yi

Observations and numerical simulations have shown that outflows generally exist in the accretion process. We revisit the thermal equilibrium solutions of black hole accretion flows by including the role of outflows. Our study focuses on the…

High Energy Astrophysical Phenomena · Physics 2022-05-18 Wen-Biao Wu , Wei-Min Gu , Mouyuan Sun

We use the standard Runge-Kutta method to solve the set of basic equations describing black hole accretion flows composed of two-temperature plasma. We do not invoke any extra energy transport mechanism such as thermal conduction and do not…

Astrophysics · Physics 2009-11-10 Ju-Fu Lu , Yi-Qing Lin , Wei-Min Gu

Two-dimensional accretion flows near black holes have been investigated by time-dependent hydrodynamical calculations. We assume that the flow is axisymmetric and that radiative losses of internal energy are negligible, so that the disc is…

Astrophysics · Physics 2015-06-24 Igor V. Igumenshchev , Xingming Chen , Marek A. Abramowicz

We show that a standard Shakura-Sunyaev accretion disc around a black hole with an accretion rate lower than the critical Eddington limit does show the instability in the radiation pressure dominated zone. We obtain this result performing…

Astrophysics · Physics 2009-11-10 V. Teresi , D. Molteni , E. Toscano

Numerical, two-dimensional, time-dependent hydrodynamical models of geometrically thick accretion discs around black holes are presented. Accretion flows with non-effective radiation cooling (ADAFs) can be both convectively stable or…

Astrophysics · Physics 2009-09-25 Igor V. Igumenshchev

General properties of advection-dominated accretion flows are discussed. Special emphasis is given to the optically thin branch of solutions, which has very high ion and electron temperatures and is thermally stable. This solution branch…

Astrophysics · Physics 2007-05-23 Ramesh Narayan

We obtain global solutions of radiatively inefficiently accretion flows around black holes. Whether and where convection develops in a flow are self-consistently determined with the mixing-length theory. The solutions can be divided into…

Astrophysics · Physics 2009-11-10 Ju-Fu Lu , Shuang-Liang Li , Wei-Min Gu

We investigate the viscous two temperature accretion discs around rotating black holes. We describe the global solution of accretion flows with a sub-Keplerian angular momentum profile, by solving the underlying conservation equations…

High Energy Astrophysical Phenomena · Physics 2015-05-14 S. R. Rajesh , Banibrata Mukhopadhyay

A toy model of a disk undergoing steady state accretion onto a black hole is presented. The disk is in a hydrostatic equilibrium for all radii r > r_{in}, with the inner disk radius located between the marginally stable and marginally bound…

Astrophysics · Physics 2007-05-23 Bohdan Paczynski

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…

There is a very popular two-zone accretion disk model that the inner part of the non-advective Keplerian disk (Shakura-Sunyaev disk) can produce hot advection-dominated accretion flow, which can generate high energy power-law radiation and…

High Energy Astrophysical Phenomena · Physics 2022-10-04 Rajiv Kumar , Ye-Fei Yuan

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…

Astrophysics · Physics 2007-05-23 G. S. Bisnovatyi-Kogan

The problem of steady-state accretion to nonrotating black holes is examined. Advection is included and generalized formulas for the radiation pressure in both the optically thick and thin cases are used. Special attention is devoted to…

High Energy Astrophysical Phenomena · Physics 2015-06-11 A. S. Klepnev , G. S. Bisnovatyi-Kogan

In order to study the outflows from accretion disks, we solve the set of hydrodynamic equations for accretion disks in the spherical coordinates ($r\theta\phi$) to obtain the explicit structure along the $\theta$ direction. Using…

High Energy Astrophysical Phenomena · Physics 2011-05-25 Cheng-Liang Jiao , Xue-Bing Wu

We present a systematic numerical study of two-dimensional axisymmetric accretion flows around black holes. The flows have no radiative cooling and are treated in the framework of the hydrodynamical approximation. The models calculated in…

Astrophysics · Physics 2016-08-30 Igor V. Igumenshchev , Marek A. Abramowicz

It has recently been demonstrated that the Shakura-Sunyaev prescription for the kinematic viscosity in an advection-dominated accretion disk yields physically reasonable solutions for the structure of the inflow close to the event horizon.…

Astrophysics · Physics 2009-11-10 Peter A. Becker , Prasad Subramanian

Accretion disks around black holes in which the shear stress is proportional to the total pressure, the accretion rate is more than a small fraction of Eddington, and the matter is distributed smoothly are both thermally and viscously…

Astrophysics · Physics 2009-10-30 J. H. Krolik
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