The three-dimensional structure of black hole accretion flows within the plunging region

Fuente: arXiv
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Main Authors: Mummery, Andrew, Stone, James M.
Format: Preprint
Published: 2024
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author Mummery, Andrew
Stone, James M.
author_facet Mummery, Andrew
Stone, James M.
contents We analyse, using new analytical models and numerical general relativistic magnetohydrodynamic simulations, the three-dimensional properties of accretion flows inside the plunging region of black hole spacetimes (i.e., at radii smaller than the innermost stable circular orbit). These simulations are of thick discs, with aspect ratios of order unity $h/r \sim 1$, and with a magnetic field geometry given by the standard low-magnetization "SANE" configuration. This work represents the first step in a wider analysis of this highly relativistic region. We show that analytical expressions derived in the "thin disc" limit describe the numerical results remarkably well, despite the large aspect ratio of the flow. We further demonstrate that accretion within this region is typically mediated via spiral arms, and that the geometric properties of these spiral structures can be understood with a simple analytical model. These results highlight how accretion within the plunging region is fundamentally two dimensional in character, which may have a number of observational implications. We derive a modified theoretical description of the pressure within the plunging region which accounts for turbulent heating and may be of use to black hole image modelling.
format Preprint
id arxiv_https___arxiv_org_abs_2407_02164
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The three-dimensional structure of black hole accretion flows within the plunging region
Mummery, Andrew
Stone, James M.
High Energy Astrophysical Phenomena
We analyse, using new analytical models and numerical general relativistic magnetohydrodynamic simulations, the three-dimensional properties of accretion flows inside the plunging region of black hole spacetimes (i.e., at radii smaller than the innermost stable circular orbit). These simulations are of thick discs, with aspect ratios of order unity $h/r \sim 1$, and with a magnetic field geometry given by the standard low-magnetization "SANE" configuration. This work represents the first step in a wider analysis of this highly relativistic region. We show that analytical expressions derived in the "thin disc" limit describe the numerical results remarkably well, despite the large aspect ratio of the flow. We further demonstrate that accretion within this region is typically mediated via spiral arms, and that the geometric properties of these spiral structures can be understood with a simple analytical model. These results highlight how accretion within the plunging region is fundamentally two dimensional in character, which may have a number of observational implications. We derive a modified theoretical description of the pressure within the plunging region which accounts for turbulent heating and may be of use to black hole image modelling.
title The three-dimensional structure of black hole accretion flows within the plunging region
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2407.02164