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Advection is believed to be the dominant cooling mechanism in optically thin advection-dominated accretion flows (ADAF's). When outflow is considered, however, the first impression is that advection should be of opposite sign in the inflow…

High Energy Astrophysical Phenomena · Physics 2023-01-24 Cheng-Liang Jiao

In this Letter we investigate the properties of advection-dominated accretion flows (ADAFs) fed by the evaporation of a Shakura-Sunyaev accretion disk (SSD). In our picture the ADAF fills the central cavity evacuated by the SSD and extends…

Astrophysics · Physics 2009-10-31 R. Turolla , C. P. Dullemond

The magnetically arrested disks (MADs) have attracted much attention in recent years. The formation of MADs are usually attributed to the accumulation of a sufficient amount of dynamically significant poloidal magnetic flux. In this work,…

High Energy Astrophysical Phenomena · Physics 2024-11-28 Jia-Wen Li , Xinwu Cao

We solved analytically viscous two-dimensional (2D) fluid equations for accretion and outflows in spherical polar coordinates ($r, \theta, \phi$) and obtained explicitly flow variables in $r-$ and $\theta -$directions around black holes…

High Energy Astrophysical Phenomena · Physics 2018-07-04 Rajiv Kumar , Wei-Min Gu

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

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

A self-similar solution for time evolution of quasi-spherical, self-gravitating accretion flows is obtained under the assumption that the generated heat by viscosity is retained in the flow. The solutions are parameterized by the ratio of…

Astrophysics · Physics 2009-11-10 Mohsen Shadmehri

Outflows and convective motions in accretion flows have been intensively discussed recently in the context of advection-dominated accretion flow (ADAF) based on two-dimensional (2D) and three-dimensional (3D) hydrodynamical simulations. We,…

Astrophysics · Physics 2007-05-23 Mami Machida , Ryoji Matsumoto , and Shin Mineshige

We investigate accretion onto a central star, with the size, rotation rate, and magnetic dipole of a young stellar object, to study the flow pattern (velocity and density) of the fluid within and outside of the disc. We perform resistive…

Solar and Stellar Astrophysics · Physics 2023-06-14 R. Mishra , M. Čemeljić , W. Kluźniak

We investigate the radial transport of magnetic flux in a thin accretion disc, the turbulence being modelled by effective diffusion coefficients (viscosity and resistivity). Both turbulent diffusion and advection by the accretion flow…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Jerome Guilet , Gordon I. Ogilvie

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, $\alpha$,…

Astrophysics · Physics 2007-05-23 A. Różańska , B. Czerny

We present the two-dimensional inflow-outflow solutions of radiation hydrodynamic (RHD) equations of supercritical accretion flows. Compared with prior studies, we include all components of the viscous stress tensor. We assume steady state…

High Energy Astrophysical Phenomena · Physics 2020-01-15 Fatemeh Zahra Zeraatgari , Amin Mosallanezhad , Ye-Fei Yuan , De-Fu Bu , Liquan Mei

We present a modified description of advection-dominated accretion flows (ADAF) with a geometrical viscosity. A simplified treatment of the dynamics of the flow in the inner relativistic part is suggested and results are compared with the…

Astrophysics · Physics 2007-05-23 T. Beckert , W. J. Duschl

We considered the effects of convection on the radiatively inefficient accretion flows (RIAF) in the presence of resistivity and toroidal magnetic field. We discussed the effects of convection on transports of angular momentum and energy.…

High Energy Astrophysical Phenomena · Physics 2015-06-04 Kazem Faghei , Mobina Omidvand

The purpose of this paper is to explore the dynamical behaviour of hot accretion flow with thermal conduction. The importance of thermal conduction on hot accretion flow is confirmed by observations of the hot gas that surrounds Sgr A$^*$…

High Energy Astrophysical Phenomena · Physics 2012-05-11 Kazem Faghei

Two significant progresses have been made in the past years on our understanding of hot accretion flows. One is that only a small fraction of accretion flow available at the outer boundary can finally falls onto the black hole while most of…

High Energy Astrophysical Phenomena · Physics 2015-06-05 Fu-Guo Xie , Feng Yuan

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

Aims: We investigate the suitability of {\alpha}-viscosity in self-similar models for self-gravitating disks with a focus on active galactic nuclei (AGN) disks. Methods: We use a self-similar approach to simplify the partial differential…

High Energy Astrophysical Phenomena · Physics 2016-03-16 Marcus Kubsch , T. F. Illenseer , W. J. Duschl

We suggest a model of the advection dominated accretion flow (ADAF) with magnetically driven outflows to explain hysteretic state transition observed in X-ray binaries (XRBs). The transition from a thin disk to an ADAF occurs when the mass…

High Energy Astrophysical Phenomena · Physics 2016-01-27 Xinwu Cao

We show that recently published assertions that advection dominated accretion flows (ADAFs) require the presence of strong winds are unfounded because they assume that low radiative efficiency in flows accreting at low rates onto black…

Astrophysics · Physics 2007-05-23 Marek A. Abramowicz , Jean-Pierre Lasota , Igor V. Igumenshchev