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We perform 3D radiation-magnetohydrodynamic simulations of the evolution of the fallback debris after a tidal disruption event. We focus on studying the effects of magnetic fields on the formation and early evolution of the accretion flow.…

High Energy Astrophysical Phenomena · Physics 2025-10-28 Maria Renee Meza , Xiaoshan Huang , Shane W. Davis , Yan-Fei Jiang

Recent observations of SgrA* by the GRAVITY instrument have astrometrically tracked infrared flares (IR) at distances of $\sim 10$ gravitational radii ($r_g$). In this paper, we study a model for the flares based on 3D general relativistic…

High Energy Astrophysical Phenomena · Physics 2021-02-03 O. Porth , Y. Mizuno , Z. Younsi , C. M. Fromm

We present results from two long-duration GRMHD simulations of advection-dominated accretion around a non-spinning black hole. The first simulation was designed to avoid significant accumulation of magnetic flux around the black hole. This…

High Energy Astrophysical Phenomena · Physics 2015-06-05 Ramesh Narayan , Aleksander Sadowski , Robert F. Penna , Akshay K. Kulkarni

The aim of this paper is to investigate the properties of accretion disks threaded by a weak vertical magnetic field, with a particular focus on the interplay between MHD turbulence driven by the magnetorotational instability (MRI) and…

High Energy Astrophysical Phenomena · Physics 2015-06-11 Sebastien Fromang , Henrik N. Latter , Geoffroy Lesur , Gordon I. Ogilvie

We use global three dimensional radiation magneto-hydrodynamical simulations to study accretion disks onto a $5\times 10^8M_{\odot}$ black hole with accretion rates varying from $\sim 250L_{Edd}/c^2$ to $1500 L_{Edd}/c^2$. We form the disks…

High Energy Astrophysical Phenomena · Physics 2019-09-11 Yan-Fei Jiang , James Stone , Shane W. Davis

The general relativistic magnetohydrodynamic (GRMHD) simulations are widely used to study accretion disk and jet dynamics around a black hole. Despite strong observational evidences for intrinsically nonlinear behavior, the interpretations…

High Energy Astrophysical Phenomena · Physics 2026-04-21 Srishty Aggarwal , Rohan Raha , Mayank Pathak , Banibrata Mukhopadhyay

In our study, we examine a 2D radiation, relativistic, magnetohydrodynamics (Rad-RMHD) accretion flows around a spinning supermassive black hole. We begin by setting an initial equilibrium torus around the black hole, with an embedded…

High Energy Astrophysical Phenomena · Physics 2024-06-18 Ramiz Aktar , Kuo-Chuan Pan , Toru Okuda

Magnetized accretion flow onto a black hole (BH) may lead to accumulation of poloidal magnetic flux across its horizon, which for high BH spin can power far-reaching relativistic jets. The BH magnetic flux is subject to a saturation…

High Energy Astrophysical Phenomena · Physics 2024-12-04 Krzysztof Nalewajko , Mateusz Kapusta , Agnieszka Janiuk

We perform three-dimensional radiation-relativistic magnetohydrodynamic (3D Rad-RMHD) simulations of accretion flows around spinning active galactic nuclei (AGNs). Our study focuses on the magnetically arrested disk (MAD) state, adopting a…

High Energy Astrophysical Phenomena · Physics 2026-03-13 Ramiz Aktar , Kuo-Chuan Pan , Toru Okuda

We report on the second phase of our study of slightly rotating accretion flows onto black holes. We consider magnetohydrodynamical (MHD) accretion flows with a spherically symmetric density distribution at the outer boundary, but with…

Astrophysics · Physics 2009-11-07 D. Proga , M. C. Begelman

In this proceeding, we provide a novel approach to study the General Relativistic Magnetohydrodynamic (GRMHD) accretion flows around rotating black holes (BHs). In doing so, we choose a sub-Keplerian distribution of angular momentum of the…

High Energy Astrophysical Phenomena · Physics 2025-03-11 Samik Mitra

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

We analyze data from a standard 3D general-relativistic magnetohydrodynamics (GRMHD) simulation, focusing on equatorial slices in order to examine the details and the evolution of the azimuthal structure of the accreting matter. During flux…

High Energy Astrophysical Phenomena · Physics 2026-04-17 Argyrios Loules , Antonios Nathanail , Ioannis Contopoulos

Dwarf novae (DNe) are accreting white dwarfs that show eruptions due to a thermal-viscous instability in the accretion disk. The outburst timescales constrain $\alpha$, the ratio of the viscous stress to the thermal pressure, and so the…

High Energy Astrophysical Phenomena · Physics 2018-12-05 Nicolas Scepi , Geoffroy Lesur , Guillaume Dubus , Mario Flock

We study the two-dimensional, time-dependent MHD of radiation-driven winds from luminous accretion disks initially threaded by a purely axial magnetic field. The radiation force is mediated primarily by spectral lines. We use ideal MHD to…

Astrophysics · Physics 2009-11-07 D. Proga

We present a global magnetohydrodynamic (MHD) three dimensional simulation of a nonradiative accretion flow originating in a pressure supported torus. The evolution is controlled by the magnetorotational instability which produces…

Astrophysics · Physics 2009-11-06 John F. Hawley , Steven A. Balbus , James M. Stone

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

Magnetically arrested accretion discs (MADs) around black holes (BH) have the potential to stimulate the production of powerful jets and account for recent ultra-high-resolution observations of BH environments. Their main properties are…

High Energy Astrophysical Phenomena · Physics 2022-02-16 Mitchell C. Begelman , Nicolas Scepi , Jason Dexter

Understanding the physics and geometry of accretion and ejection around super massive black holes (SMBHs) is important to understand the evolution of active galactic nuclei (AGN) and therefore of the large scale structures of the Universe.…

Astrophysics of Galaxies · Physics 2019-11-11 Margherita Giustini , Daniel Proga

Accretion disks are likely threaded by external vertical magnetic flux, which enhances the level of turbulence via the magnetorotational instability (MRI). Using shearing-box simulations, we find that such external magnetic flux also…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Xue-Ning Bai , James M. Stone