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We present the results of global three dimensional magneto-hydrodynamic simulations of black hole accretion flows. We focus on the dependence of numerical results on the gas temperature Tout supplied from the outer region. General…

Astrophysics · Physics 2015-05-13 Mami Machida , Ryoji Matsumoto

The prevalence and consequences of convection perpendicular to the plane of accretion discs have been discussed for several decades. Recent simulations combining convection and the magnetorotational instability have given fresh impetus to…

Solar and Stellar Astrophysics · Physics 2018-08-08 Loren E. Held , Henrik N. Latter

We present 3D adaptive mesh refinement MHD simulations of an isolated galaxy cluster that include injection of kinetic, thermal, and magnetic energy via a central active galactic nucleus (AGN) in order to study and evaluate the role that…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 P. M. Sutter , H. -Y. Yang , P. M. Ricker , G. Foreman , D. Pugmire

We analyze three-dimensional magnetohydrodynamic (MHD) simulations of a nonradiative accretion flow around a black hole using a pseudo-Newtonian potential. The flow originates from a torus initially centered at 100 gravitational…

Astrophysics · Physics 2009-11-07 John F. Hawley , Steven A. Balbus

Convection has been discussed in the field of accretion discs for several decades, both as a means of angular momentum transport and also because of its role in controlling discs' vertical structure via heat transport. If the gas is…

Solar and Stellar Astrophysics · Physics 2021-04-21 Loren E. Held , Henrik N. Latter

We present the first dynamical model of plasma accretion onto traversable wormholes by performing General Relativistic magneto-hydrodynamical (GRMHD) simulations of the flow on both sides of the wormhole. We evolve the ideal MHD equations…

High Energy Astrophysical Phenomena · Physics 2024-05-14 Luciano Combi , Huan Yang , Eduardo Gutierrez , Scott C. Noble , Gustavo E. Romero , Manuela Campanelli

We discuss results of global 3D MHD simulations of accretion on to a rotating magnetized star with a tilted dipole magnetic field, where the accretion is driven by the magneto-rotational instability (MRI). The simulations show that…

Solar and Stellar Astrophysics · Physics 2015-06-03 M. M. Romanova , G. V. Ustyugova , A. V. Koldoba , R. V. E. Lovelace

We summarize results from a survey of radiation-dominated black hole accretion flows across a wide range of mass accretion rates, as well as two values of black hole spin and initial magnetic field geometry. These models apply an algorithm…

High Energy Astrophysical Phenomena · Physics 2025-09-16 Lizhong Zhang , James M. Stone , Patrick D. Mullen , Shane W. Davis , Yan-Fei Jiang , Christopher J. White

We investigate acceleration and propagation processes of high-energy particles inside hot accretion flows. The magnetorotational instability (MRI) creates turbulence inside accretion flows, which triggers magnetic reconnection and may…

High Energy Astrophysical Phenomena · Physics 2019-12-03 Shigeo S. Kimura , Kengo Tomida , Kohta Murase

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…

We theoretically investigate the magnetic flux transport in geometrically thick accretion discs which may form around black holes. We utilize a two-dimensional (2D) kinematic mean-field model for poloidal field transport which is governed…

High Energy Astrophysical Phenomena · Physics 2023-10-02 Ryoya Yamamoto , Shinsuke Takasao

We present three-dimensional numerical magnetohydrodynamic simulations of radiatively inefficient spherical accretion onto a black hole. The simulations are initialized with a Bondi flow, and with a weak, dynamically unimportant,…

Astrophysics · Physics 2009-11-06 Igor V. Igumenshchev , Ramesh Narayan

A large-scale closed magnetic field can transfer angular momentum and energy between a black hole (BH) and its surrounding accretion flow. We investigate the effects of this magnetic coupling (MC) process on the dynamics of a hot accretion…

Astrophysics · Physics 2009-11-13 R. Y. Ma , F. Yuan , D. X. Wang

We perform global unstratified 3D magnetohydrodynamic simulations of an astrophysical boundary layer (BL) -- an interface region between an accretion disk and a weakly magnetized accreting object such as a white dwarf -- with the goal of…

Solar and Stellar Astrophysics · Physics 2015-06-12 Mikhail A. Belyaev , Roman R. Rafikov , James. M. Stone

Sagittarius A$^\ast$ is a compact radio source at the center of the Milky Way that has not conclusively shown evidence for the presence of a relativistic jet. Nevertheless, indirect methods at radio frequencies do indicate consistent…

High Energy Astrophysical Phenomena · Physics 2024-09-11 Jesse Vos , Jordy Davelaar , Hector Olivares , Christiaan Brinkerink , Heino Falcke

We show that the removal of angular momentum is possible in the presence of large scale magnetic stresses in geometrically thick, advective, sub-Keplerian accretion flows around black holes in steady-state, in the complete absence of…

High Energy Astrophysical Phenomena · Physics 2015-07-03 Banibrata Mukhopadhyay , Koushik Chatterjee

Depending on the astrophysical source and its environment, the accretion flows can exhibit a variety of behaviors and characteristics in accordance with the type of solutions. We study low-angular-momentum accretion flows onto black holes…

High Energy Astrophysical Phenomena · Physics 2025-08-01 Indu K. Dihingia , Akhil Uniyal , Yosuke Mizuno

We study the evolution of magnetic fields in accretion flows around six different sink particles in a global star formation simulation. Using the adaptive mesh refinement capabilities of \ramses, the vicinity of the sinks is resolved with a…

Solar and Stellar Astrophysics · Physics 2017-11-01 Michael Kuffmeier , Farrukh Nauman

We studied magnetically arrested disks (MAD) around rotating black holes (BH), under the influence of radiative cooling. We introduce a critical value of the mass accretion rate $\dot M_{\rm crit}$ for which the cooling by the synchrotron…

High Energy Astrophysical Phenomena · Physics 2025-02-18 Akshay Singh , Damien Bégué , Asaf Pe'er

During the main phase of evolution of a protoplanetary disk, accretion regulates the inner-disk properties, such as the temperature and mass distribution, and in turn, the physical conditions associated with planet formation. The driving…

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