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Accretion flows onto underluminous black holes, such as Sagittarius A* at the center of our galaxy, are dilute (mildly collisional to highly collisionless), optically thin, and radiatively inefficient. Therefore, the accretion properties of…

High Energy Astrophysical Phenomena · Physics 2015-05-28 Tanim Islam

Radiation pressure dominated accretion discs around compact objects may have turbulent velocities that greatly exceed the electron thermal velocities within the disc. Bulk Comptonization by the turbulence may therefore dominate over thermal…

High Energy Astrophysical Phenomena · Physics 2016-04-20 J. Kaufman , O. M. Blaes

This study investigates the thermal stability of thin accretion disks in high-energy astrophysical systems, incorporating the effects of magnetic fields, winds, and coronae. We analyze how these factors influence disk stability, focusing on…

High Energy Astrophysical Phenomena · Physics 2025-01-28 Arezoo Tajmohamadi , Shahram Abbassi

The dynamical response of edge waves under the influence of self-gravity is examined in an idealized two-dimensional model of a proto-stellar disc, characterized in steady state as a rotating vertically infinite cylinder of fluid with…

Solar and Stellar Astrophysics · Physics 2016-04-27 Ron Yellin-Bergovoy , Eyal Heifetz , Orkan M. Umurhan

We consider a class of steady-state self-gravitating accretion disks for which efficient cooling mechanisms are assumed to operate so that the disk is self-regulated at a condition of approximate marginal Jeans stability. In an earlier…

Astrophysics · Physics 2007-05-23 G. Bertin , G. Lodato

We demonstrate that in N-body simulations of isolated disc galaxies there is numerical vertical heating which slowly increases the vertical velocity dispersion and the disc thickness. Even for models with over a million particles in a disc,…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 S. A. Rodionov , N. Ya. Sotnikova

The standard accretion discs are known to be thermally and viscously unstable over a certain range of temperatures. In the inner disc regions there may develop radiation pressure driven instability, which is possibly related to the rapid…

Astrophysics · Physics 2007-05-23 Agnieszka Janiuk , Bozena Czerny

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

The steady-state structure of a disc with a corona is analyzed when the vertical component of the gravitational force due to the self-gravity of the disc is considered. For the energy exchange between the disc and the corona, we assume a…

Astrophysics · Physics 2009-11-13 Fazeleh Khajenabi , Peter Duffy

A heat flux in a high-$\beta$ plasma with low collisionality triggers the whistler instability. Quasilinear theory predicts saturation of the instability in a marginal state characterized by a heat flux that is fully controlled by electron…

High Energy Astrophysical Phenomena · Physics 2018-07-18 S. Komarov , A. Schekochihin , E. Churazov , A. Spitkovsky

A linear stability analysis of ionized discs with a temperature gradient and an external axial magnetic field is presented. It is shown that both hydromagnetic and thermomagnetic effects can lead to the amplification of waves and make discs…

Astrophysics of Galaxies · Physics 2010-04-21 Edward Liverts , Michael Mond , Vadim Urpin

We investigate the thermal stability of optically thin, two-temperature, radiative cooling-dominated accretion disks. Our linear analysis shows that the disk is thermally unstable without magnetic fields, which agrees with previous…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Xiao-Fei Yu , Wei-Min Gu , Tong Liu , Ren-Yi Ma , Ju-Fu Lu

We study the stability of poloidal magnetic fields anchored in a thin accretion disc. The two-dimensional hydrodynamics in the disc plane is followed by a grid-based numerical simulation including the vertically integrated magnetic forces.…

Astrophysics · Physics 2015-06-24 R. Stehle , H. C. Spruit

We study accretion driven turbulence for different inflow velocities in star forming filaments using the code ramses. Filaments are rarely isolated objects and their gravitational potential will lead to radially dominated accretion. In the…

Astrophysics of Galaxies · Physics 2018-08-06 Stefan Heigl , Andreas Burkert , Matthias Gritschneder

We investigate the structure of accretion disks around massive protostar applying steady state models of thin disks. The thin disk equations are solved with proper opacities for dust and gas taking into account the huge temperature…

Solar and Stellar Astrophysics · Physics 2009-08-17 B. Vaidya , C. Fendt , H. Beuther

The irradiation of protoplanetary discs by central stars is the main heating mechanism for discs, resulting in their flared geometric structure. In a series of papers, we investigate the deep links between 2D self-consistent disc structure…

Earth and Planetary Astrophysics · Physics 2015-05-14 Yasuhiro Hasegawa , Ralph E. Pudritz

Recent work has shown that the speed of the cooling front in soft X-ray transients may be an important clue in understanding the nature of accretion disk viscosity. In a previous paper (Vishniac and Wheeler 1996) we derived the scaling law…

Astrophysics · Physics 2009-10-30 Ethan T. Vishniac

Protoplanetary disks fragment due to gravitational instability when there is enough mass for self-gravitation, described by the Toomre parameter, and when heat can be lost at a rate comparable to the local dynamical timescale, described by…

Earth and Planetary Astrophysics · Physics 2015-12-08 Hans Baehr , Hubert Klahr

We study particle dynamics in self-gravitating gaseous discs with a simple cooling law prescription via two-dimensional simulations in the shearing sheet approximation. It is well known that structures arising in the gaseous component of…

Earth and Planetary Astrophysics · Physics 2015-06-19 P. G. Gibbons , G. R. Mamatsashvili , W. K. M. Rice

An instability can potentially operate in highly irradiated disks where the disk sharply transitions from being radially transparent to opaque (the 'transition region'). Such conditions may exist at the inner edges of transitional disks…

Earth and Planetary Astrophysics · Physics 2015-05-13 Jeffrey Fung , Pawel Artymowicz