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We study super-Eddington accretion flows onto black holes using a global three dimensional radiation magneto-hydrodynamical simulation. We solve the time dependent radiative transfer equation for the specific intensities to accurately…

High Energy Astrophysical Phenomena · Physics 2014-11-14 Yan-Fei Jiang , James M. Stone , Shane W. Davis

Radiation dominated accretion disks are likely to be subject to the ``photon bubble'' instability, which may lead to strong density inhomogeneities on scales much shorter than the disk scale height. Such disks -- and magnetized,…

Astrophysics · Physics 2009-11-07 Mateusz Ruszkowski , Mitchell C. Begelman

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-consistent solution for a thin accretion disk with turbulent convection is presented. The disk viscosity and the convective flux are derived from a physical model for turbulence, and expressed in terms of the local physical…

Astrophysics · Physics 2009-10-28 Itzhak Goldman , Amri Wandel

A model for axisymmetric magnetized accretion flow is proposed. The dominant mechanism of energy dissipation is assumed to be the magnetic diffusivity due to turbulence in the accretion flow. In analogy to the advection-dominated accretion…

Astrophysics · Physics 2009-11-07 Mohsen Shadmehri

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

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

Based on no-outflow assumption, we investigate steady state, axisymmetric, optically thin accretion flows in spherical coordinates. By comparing the vertically integrated advective cooling rate with the viscous heating rate, we find that…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Wei-Min Gu

The global structure of optically thin hot accretion disks with radial advection included has been investigated. We solve the full energy conservation equation explicitly and construct the radial structure of the disk. It is found that…

Astrophysics · Physics 2016-08-30 Xingming Chen

Advection-dominated, high-temperature, quasi-spherical accretion flow onto a compact object, recently considered by a number of authors, assume that the dissipation of turbulent energy of the flow heats the ions and that the dissipated…

Astrophysics · Physics 2009-10-30 G. S. Bisnovatyi-Kogan , R. V. E. Lovelace

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

We consider hot, two-temperature, viscous accretion onto a rotating, unmagnetized neutron star. We assume Coulomb coupling betweenthe protons and electrons, and free-free cooling from the electrons. We show that the accretion flow has an…

Astrophysics · Physics 2009-10-31 Mikhail V. Medvedev , Ramesh Narayan

We solve the two-dimensional hydrodynamic equations of hot accretion flow in the presence of the thermal conduction. The flow is assumed to be in steady-state and axisymmetric, and self-similar approximation is adopted in the radial…

High Energy Astrophysical Phenomena · Physics 2021-03-24 Amin Mosallanezhad , Fatemeh Zahra Zeraatgari , Liquan Mei , De-Fu Bu

We consider the effects of advection and radial gradients of pressure and radial drift velocity on the structure of optically thick accretion disks. We concentrate our efforts on highly viscous disks, $\alpha=1.0$, with large accretion…

Astrophysics · Physics 2007-05-23 I. V. Artemova , G. S. Bisnovatyi-Kogan , G. Bjoernsson , I. D. Novikov

(Abridged) We present two-dimensional hydrodynamical simulations of slowly rotating gas that is under the influence of the gravity of a super massive black hole and is irradiated by a thin UV accretion disc and a spherical X-ray corona. We…

Astrophysics of Galaxies · Physics 2015-05-13 Ryuichi Kurosawa , Daniel Proga

The metal-poor gas continuously accreting onto the discs of spiral galaxies is unlikely to arrive from the intergalactic medium (IGM) with exactly the same rotation velocity as the galaxy itself and even a small angular momentum mismatch…

Astrophysics of Galaxies · Physics 2015-12-02 Gabriele Pezzulli , Filippo Fraternali

Standard models of radiation supported accretion disks generally assume that diffusive radiation flux is solely responsible for vertical heat transport. This requires that heat must be generated at a critical rate per unit volume if the…

High Energy Astrophysical Phenomena · Physics 2015-05-27 Omer Blaes , Julian H. Krolik , Shigenobu Hirose , Natalia Shabaltas

We consider an extreme case of disc accretion onto a gravitating centre when the viscosity in the disc is negligible. The angular momentum and the rotational energy of the accreted matter is carried out by a magnetized wind outflowing from…

Astrophysics · Physics 2010-04-28 Sergei Bogovalov , Stanislav Kelner

We study the accretion flow of a hot gas captured by the black hole gravity in the presence of a thin cold accretion disk. Such geometrical arrangement is expected in Active Galactic Nuclei (AGN) and in galactic X-ray binary systems because…

Astrophysics · Physics 2007-05-23 Sergei Nayakshin

We perform time-dependent, 2DHD numerical simulations to study the dynamics of a slowly rotating accretion flow from sub-pc to pc scales under the irradiation from the central AGN. Compared to previous work, we improve the calculation of…

High Energy Astrophysical Phenomena · Physics 2015-06-15 Chao Liu , Feng Yuan , Jeremiah P. Ostriker , Zhaoming Gan , Xiaohong Yang