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Multiple models have been suggested over the years to explain the structure and support of accretion disks around supermassive black holes, from the standard thin thermal-pressure-dominated $\alpha$-disk model to more recent models that…

High Energy Astrophysical Phenomena · Physics 2026-04-28 Yashvardhan Tomar , Philip F. Hopkins , Kyle Kremer

Recent numerical cosmological radiation-magnetohydrodynamic-thermochemical-star formation simulations have resolved the formation of quasar accretion disks with Eddington or super-Eddington accretion rates onto supermassive black holes…

Black holes (BHs) surrounded by accretion disks are present in the Universe at different scales of masses, from microquasars up to the active galactic nuclei (AGNs). The current picture remains ad hoc due to the complexity of the magnetic…

High Energy Astrophysical Phenomena · Physics 2017-07-19 Mikołaj Grzędzielski , Agnieszka Janiuk , Bożena Czerny , Qingwen Wu

Magnetic effects have long been considered a possible factor in stabilizing the outer regions of active galactic nuclei (AGN) accretion disks against gravitational instability (GI). However, the computational demands of testing this…

High Energy Astrophysical Phenomena · Physics 2025-08-26 Hannalore J. Gerling-Dunsmore , Mitchell C. Begelman , Jacob B. Simon , Philip J. Armitage

The relations among the relative changes of surface density, temperature, disk height and vertical integrated pressure in three kinds of thermally unstable accretion disks were quantitatively investigated by assuming local perturbations.…

Astrophysics · Physics 2009-10-30 Xue-Bing Wu

In this paper, we develop the analysis of a two-dimensional magnetohydrodynamical configuration for an axially symmetric and rotating plasma (embedded in a dipole like magnetic field), modeling the structure of a thin accretion disk around…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Giovanni Montani , Riccardo Benini

We investigate the dynamics of the accretion disks of young stars with fossil large-scale magnetic field. The author's magnetohydrodynamic (MHD) model of the accretion disks is generalized to consider the dynamical influence of the magnetic…

Solar and Stellar Astrophysics · Physics 2022-12-28 Sergey A. Khaibrakhmanov , Alexander E. Dudorov

We present the results of a series of radiation-MHD simulations of a local patch of an accretion disk, with fixed vertical gravity profile but with different surface mass densities and a broad range of radiation to gas pressure ratios. Each…

High Energy Astrophysical Phenomena · Physics 2015-05-13 Shigenobu Hirose , Omer Blaes , Julian H. Krolik

We analyze a two dimensional viscoresistive magnetohydrodynamical (MHD) model for a thin accretion disk which reconciles the crystalline structure outlined in [Coppi(2005), Coppi and Rousseau(2006)] with real microscopic and macroscopic…

High Energy Astrophysical Phenomena · Physics 2015-06-03 Riccardo Benini , Giovanni Montani , Jacopo Petitta

We examine the evolution of the Parker instability in galactic disks using 3D numerical simulations. We consider a local Cartesian box section of a galactic disk, where gas, magnetic fields and cosmic rays are all initially in a…

Astrophysics of Galaxies · Physics 2015-12-24 Luiz Felippe S. Rodrigues , Graeme R. Sarson , Anvar Shukurov , Paul J. Bushby , Andrew Fletcher

We use three dimensional magnetohydrodynamic simulations to study the structure of the boundary layer between an accretion disc and a non-rotating, unmagnetized star. Under the assumption that cooling is efficient, we obtain a narrow but…

Astrophysics · Physics 2009-11-07 Philip J. Armitage

Using numerical MHD simulations, we have studied the evolution of the magnetorotational instability in stratified accretion disks in which the ionization fraction (and therefore resistivity) varies substantially with height. This model is…

Astrophysics · Physics 2009-11-07 Timothy Fleming , James M. Stone

We carried out three-dimensional global resistive magnetohydrodynamic (MHD) simulations of the cooling instability in optically thin hot black hole accretion flows by assuming bremsstrahlung cooling. General relativistic effects are…

Astrophysics · Physics 2015-06-24 Mami Machida , Kenji Nakamura , Ryoji Matsumoto

An approximate analytic one-dimensional model is constructed, for the accretion disk boundary layer surrounding a neutron star whose low magnetic field does not affect the process of accretion. A high luminosity model is considered, with…

High Energy Astrophysical Phenomena · Physics 2025-11-25 G. S. Bisnovatyi-Kogan

The standard equilibrium for radiation-dominated accretion disks has long been known to be viscously, thermally, and convectively unstable, but the nonlinear development of these instabilities---hence the actual state of such disks---has…

Astrophysics · Physics 2009-11-06 Eric Agol , Julian Krolik , Neal Turner , James Stone

We present a detailed study of the growth of the Parker instability in a differentially rotating disk embedded in an azimuthal equilibrium magnetic field, such as the interstellar gas or an accretion disk. Basic properties of the…

Astrophysics · Physics 2007-05-23 T. Foglizzo , M. Tagger

We present global 3D MHD simulations of geometrically thin but unstratified accretion disks in which a near Keplerian disk rotates between two bounding regions with initial rotation profiles that are stable to the MRI. The inner region…

Astrophysics · Physics 2015-05-27 Adriane Steinacker , John C. B. Papaloizou

Abridged: Recent simulations have explored different ways to form accretion disks around low-mass stars. We aim to present observables to differentiate a rotationally supported disk from an infalling rotating envelope toward deeply embedded…

Solar and Stellar Astrophysics · Physics 2015-04-29 Daniel Harsono , Ewine van Dishoeck , Simon Bruderer , Zhi-Yun Li , Jes Jorgensen

We present three-dimensional (3-D) hydrodynamical simulations of gas flows in the vicinity of an active galactic nucleus (AGN) powered by a precessing accretion disk. We consider the effects of the radiation force from such a disk on its…

Astrophysics · Physics 2009-11-13 Ryuichi Kurosawa , Daniel Proga

We study the long-term thermal stability of radiation dominated disks in which the vertical structure is determined self-consistently by the balance of heating due to dissipation of MHD turbulence driven by the magneto-rotational…

High Energy Astrophysical Phenomena · Physics 2013-11-07 Yan-Fei Jiang , James Stone , Shane Davis