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We present a 3-D ideal MHD simulation of magnetospheric accretion onto a non-rotating star. The accretion process unfolds with intricate 3-D structures driven by various mechanisms. First, the disc develops filaments at the magnetospheric…

Solar and Stellar Astrophysics · Physics 2023-12-18 Zhaohuan Zhu , James M. Stone , Nuria Calvet

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 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 numerically evolve turbulence driven by the magnetorotational instability (MRI) in a 3D, unstratified shearing box and study its structure using two-point correlation functions. We confirm Fromang and Papaloizou's result that shearing…

Astrophysics of Galaxies · Physics 2011-02-11 Xiaoyue Guan , Charles F. Gammie , Jacob B. Simon , Bryan M. Johnson

Accretion disks in Active Galactic Nuclei (AGN) are predicted to become gravitationally unstable substantially interior to the black hole's sphere of influence, at radii where the disk is simultaneously unstable to the magnetorotational…

High Energy Astrophysical Phenomena · Physics 2025-07-30 Tsun Hin Navin Tsung , Mitchell C. Begelman , Philip J. Armitage , Yan-Fei Jiang , Hannalore J. Gerling-Dunsmore

Hydromagnetic stresses in accretion discs have been the subject of intense theoretical research over the past one and a half decades. Most of the disc simulations have assumed a small initial magnetic field and studied the turbulence that…

Astrophysics · Physics 2009-11-13 Anders Johansen , Yuri Levin

The standard thin disk model predicts that when the accretion rate is over a small fraction of the Eddington rate, which corresponds to $L \ga 0.06 L_{Edd}$, the inner region of the disk is radiation-pressure-dominated and thermally…

High Energy Astrophysical Phenomena · Physics 2015-05-27 Sheng-Ming Zheng , Feng Yuan , Wei-Min Gu , Ju-Fu Lu

We describe the effects of both magnetic buoyancy and differential rotation on a disc of isothermal gas embedded in a purely azimuthal magnetic field, in order to study the evolution and interplay of Parker and shearing instabilities. Both…

Astrophysics · Physics 2016-08-30 Thierry Foglizzo , Michel Tagger

We present results of a set of three-dimensional, general relativistic radiation magnetohydrodynamics simulations of thin accretion discs around a non-rotating black hole to test their thermal stability. We consider two cases, one that is…

High Energy Astrophysical Phenomena · Physics 2016-09-21 B. Mishra , P. C. Fragile , L. C. Johnson , W. Kluźniak

We studied a steadily accreting, geometrically thick disk model that selfconsistently takes into account selfgravitation of the polytropic gas, its interaction with the radiation and the mass accretion rate. The accreting mass is injected…

Solar and Stellar Astrophysics · Physics 2012-04-19 Patryk Mach , Edward Malec

We present the results of four three-dimensional radiation magnetohydrodynamic simulations of accretion disks around a $10^8$ solar mass black hole, which produce the far ultraviolet spectrum peak and demonstrate a robust physical mechanism…

High Energy Astrophysical Phenomena · Physics 2025-05-16 Yan-Fei Jiang , Omer Blaes , Ish Kaul , Lizhong Zhang

An accretion disk in an Active Galactic Nucleus (AGN) harbors and shields dust from external illumination: at the mid-plane of the disk around a $M_{{\rm BH}}=10^{7}M_{\odot}$ black hole, dust can exist at $0.1$pc from the black hole,…

Astrophysics of Galaxies · Physics 2021-04-07 Anton Dorodnitsyn , Tim Kallman

We analyse the two-dimensional MHD configurations characterising the steady state of the accretion disk on a highly magnetised neutron star. The model we describe has a local character and represents the extension of the crystalline…

High Energy Astrophysical Phenomena · Physics 2014-11-20 Giovanni Montani , Riccardo Benini

We examine heating and cooling in protostellar disks using 3-D radiation-MHD calculations of a patch of the Solar nebula at 1 AU, employing the shearing-box and flux-limited radiation diffusion approximations. The disk atmosphere is ionized…

Earth and Planetary Astrophysics · Physics 2015-05-27 S. Hirose , N. J. Turner

The vertical structure of the accretion disks of young stars with fossil large-scale magnetic field is studied. The equations of magnetostatic equilibrium of the disk are solved taking into account the stellar gravity, gas and magnetic…

Solar and Stellar Astrophysics · Physics 2022-10-25 Sergey A. Khaibrakhmanov , Alexander E. Dudorov , Anton I. Vasyunin , Mikhail Yu. Kiskin

The physical modeling of the accretion disk boundary layer, the region where the disk meets the surface of the accreting star, usually relies on the assumption that angular momentum transport is opposite to the radial angular frequency…

High Energy Astrophysical Phenomena · Physics 2012-11-28 Chi-kwan Chan , Martin E. Pessah

We present numerical spectral and vertical structure calculations appropriate for near-Eddington-luminosity, radiation-pressure-dominated accretion disks around stellar-mass black holes. We cover a wide range of black hole spins and…

High Energy Astrophysical Phenomena · Physics 2018-10-31 Theodore Dezen , Bryan Flores

We investigate the effects of a large-scale magnetic field with open field lines on the steady-state structure of a radiation-dominated accretion disk, using self-similarity technique. The disk is supposed to be turbulent and possesses an…

Astrophysics · Physics 2009-11-11 Mohsen Shadmehri , Fazeleh Khajenabi

Accretion disks around supermassive black holes have regions where the Rosseland mean opacity can be much larger than the electron scattering opacity primarily due to the large number of bound-bound transitions in iron. We study the effects…

High Energy Astrophysical Phenomena · Physics 2016-08-17 Yan-Fei Jiang , Shane Davis , James Stone

Disk accretion to rotating stars with complex magnetic fields is investigated using full three-dimensional magnetohydrodynamic (MHD) simulations. The studied magnetic configurations include superpositions of misaligned dipole and quadrupole…

Astrophysics · Physics 2009-11-13 M. Long , M. M. Romanova , R. V. E. Lovelace