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Magnetically arrested accretion discs (MADs), where the magnetic pressure in the inner disc is dynamically important, provide an alternative mechanism for regulating accretion to what is commonly assumed in black hole systems. We show that…

High Energy Astrophysical Phenomena · Physics 2015-06-18 Jason Dexter , Jonathan C. McKinney , Sera Markoff , Alexander Tchekhovskoy

We discuss the importance of large scale strong magnetic field in the removal of angular momentum outward, as well as the possible origin of different kinds of magnetic barrier in advective, geometrically thick, sub-Keplerian accretion…

High Energy Astrophysical Phenomena · Physics 2018-02-28 Tushar Mondal , Banibrata Mukhopadhyay

The magnetically arrested disks (MADs) have attracted much attention in recent years. The formation of MADs are usually attributed to the accumulation of a sufficient amount of dynamically significant poloidal magnetic flux. In this work,…

High Energy Astrophysical Phenomena · Physics 2024-11-28 Jia-Wen Li , Xinwu Cao

The dynamics and structure of accretion disks, which accumulate the vertical magnetic field in the centers, are investigated using two- and three-dimensional MHD simulations. The central field can be built up to the equipartition level and…

Astrophysics · Physics 2009-11-13 Igor V. Igumenshchev

In accretion disks with large-scale ordered magnetic fields, the magnetorotational instability (MRI) is marginally suppressed, so other processes may drive angular momentum transport leading to accretion. Accretion could then be driven by…

High Energy Astrophysical Phenomena · Physics 2018-05-16 Megan D. Marshall , Mark J. Avara , Jonathan C. McKinney

The study of Magnetically Arrested Disks (MAD) attract strong interest in recent years, as these disk configurations were found to generate strong jets as observed in many accreting systems. Here, we present the results of 14 general…

High Energy Astrophysical Phenomena · Physics 2023-10-12 G. -Q. Zhang , D. Bégué , A. Pe'er , B. -B. Zhang

Recent results of the event horizon-scale images of M87* and Sagittarius A* from the Event Horizon Telescope Collaboration show that strong magnetic fields are likely present around the central black holes (BHs) in these sources.…

High Energy Astrophysical Phenomena · Physics 2025-09-19 Koushik Chatterjee , Matthew Liska , Alexander Tchekhovskoy , Sera Markoff , Ramesh Narayan

Magnetically-arrested disks (MADs) appear when accretion flows are supplied with a sufficient amount of magnetic flux. In this work, we use results of magnetohydrodynamic simulations to set the configuration of the magnetic field and…

High Energy Astrophysical Phenomena · Physics 2020-01-31 Fu-Guo Xie , Andrzej A. Zdziarski

Strongly magnetized accretion discs around black holes have attractive features that may explain enigmatic aspects of X-ray binary behaviour. The structure and evolution of these discs are governed by a dynamo-like mechanism, which channels…

High Energy Astrophysical Phenomena · Physics 2016-02-03 Greg Salvesen , Jacob B. Simon , Philip J. Armitage , Mitchell C. Begelman

Accretion discs properties should deviate from standard theory when magnetic pressure exceeds the thermal pressure. To quantify these deviations, we present a systematic study of the dynamical properties of magnetically arrested discs…

High Energy Astrophysical Phenomena · Physics 2023-10-26 Nicolas Scepi , Mitchell C. Begelman , Jason Dexter

Magnetic fields regulate black hole (BH) accretion, governing both inflow and outflow dynamics. When a BH accumulates substantial vertical magnetic flux, it enters the magnetically arrested disk (MAD) state, where dynamically important…

High Energy Astrophysical Phenomena · Physics 2025-09-18 Koushik Chatterjee , Nicholas Kaaz , Matthew Liska , Alexander Tchekhovskoy , Sera Markoff

We present the results of nine simulations of radiatively-inefficient magnetically arrested disks (MADs) across different values of the black hole spin parameter $a_*$: $-0.9$, $-0.7$, $-0.5$, $-0.3$, 0, 0.3, 0.5, 0.7, and 0.9. Each…

High Energy Astrophysical Phenomena · Physics 2022-02-16 Ramesh Narayan , Andrew Chael , Koushik Chatterjee , Angelo Ricarte , Brandon Curd

Simulations and analytic arguments suggest that the turbulence driven by magnetorotational instability (MRI) in accretion discs can amplify the toroidal (azimuthal) component of the magnetic field to a point at which magnetic pressure…

Astrophysics · Physics 2008-11-26 M. C. Begelman , J. E. Pringle

Polarisation measurements by the Event Horizon Telescope from M87$^{\ast}$ and Sgr A$^\ast$ suggest that there is a dynamically strong, ordered magnetic field, typical of what is expected of a magnetically arrested accretion disk (MAD). In…

High Energy Astrophysical Phenomena · Physics 2024-07-29 León Salas , Gibwa Musoke , Koushik Chatterjee , Sera Markoff , Oliver Porth , Matthew Liska , Bart Ripperda

Motivated by indirect observational evidence for strongly magnetized accretion discs around black holes, and the novel theoretical properties of such solutions, we investigate how a strong magnetization state can develop and persist. To…

High Energy Astrophysical Phenomena · Physics 2016-06-01 Greg Salvesen , Philip J. Armitage , Jacob B. Simon , Mitchell C. Begelman

Black hole (BH) spin can play an important role in galaxy evolution by controlling the amount of energy and momentum ejected from near the BH into the surroundings. We focus on radiatively-inefficient and geometrically-thick…

High Energy Astrophysical Phenomena · Physics 2024-04-22 Beverly Lowell , Jonatan Jacquemin-Ide , Alexander Tchekhovskoy , Alex Duncan

We discuss the problem of the formation of a large-scale magnetic field in the accretion disks around black holes, taking into account the nonuniform vertical structure of the disk. The high electrical conductivity of the outer layers of…

High Energy Astrophysical Phenomena · Physics 2011-04-27 G. S. Bisnovatyi-Kogan , R. V. E. Lovelace

Accretion near black holes (BHs) is multidimensional, with turbulence, resistivity, thermal transport, and dust dynamics all playing essential roles. In cold accretion discs (ADs) or the region of an AD where magnetic fields (MFs) are…

High Energy Astrophysical Phenomena · Physics 2025-10-30 Asish Jyoti Boruah , Liza Devi , Biplob Sarkar

General-relativistic magneto-hydrodynamical (GRMHD) simulations of accreting black holes suggest that the accretion flows form toroidal structures embedded in a large scale component of magnetic field, which becomes organized on…

High Energy Astrophysical Phenomena · Physics 2023-12-08 Petra Suková , Michal Zajaček , Vladimír Karas

The conventional accretion disk lore is that magnetized turbulence is the principal angular momentum transport process that drives accretion. However, when dynamically important large-scale magnetic fields thread an accretion disk, they can…

High Energy Astrophysical Phenomena · Physics 2024-04-24 Vikram Manikantan , Nicholas Kaaz , Jonatan Jacquemin-Ide , Gibwa Musoke , Koushik Chatterjee , Matthew Liska , Alexander Tchekhovskoy
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