An Analytic Model For Magnetically-Dominated Accretion Disks

Fuente: arXiv
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Autori principali: Hopkins, Philip F., Squire, Jonathan, Quataert, Eliot, Murray, Norman, Su, Kung-Yi, Steinwandel, Ulrich P., Kremer, Kyle, Faucher-Giguere, Claude-Andre, Wellons, Sarah
Natura: Preprint
Pubblicazione: 2023
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author Hopkins, Philip F.
Squire, Jonathan
Quataert, Eliot
Murray, Norman
Su, Kung-Yi
Steinwandel, Ulrich P.
Kremer, Kyle
Faucher-Giguere, Claude-Andre
Wellons, Sarah
author_facet Hopkins, Philip F.
Squire, Jonathan
Quataert, Eliot
Murray, Norman
Su, Kung-Yi
Steinwandel, Ulrich P.
Kremer, Kyle
Faucher-Giguere, Claude-Andre
Wellons, Sarah
contents 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 (SMBHs) down to a few hundred gravitational radii. These 'flux-frozen' and hyper-magnetized disks appear to be qualitatively distinct from classical $α$ disks and magnetically-arrested disks: the midplane pressure is dominated by toroidal magnetic fields with plasma $β\ll 1$ powered by advection of magnetic flux from the interstellar medium (ISM), and they are super-sonically and trans-Alfvenically turbulent with cooling times short compared to dynamical times yet remain gravitationally stable owing to magnetic support. In this paper, we present a simple analytic similarity model for such disks. For reasonable assumptions, the model is entirely specified by the boundary conditions (inflow rate at the BH radius of influence [BHROI]). We show that the scalings from this model are robust to various detailed assumptions, agree remarkably well with the simulations (given their simplicity), and demonstrate the self-consistency and gravitational stability of such disks even in the outer accretion disk (approaching the BHROI) at hyper-Eddington accretion rates.
format Preprint
id arxiv_https___arxiv_org_abs_2310_04507
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle An Analytic Model For Magnetically-Dominated Accretion Disks
Hopkins, Philip F.
Squire, Jonathan
Quataert, Eliot
Murray, Norman
Su, Kung-Yi
Steinwandel, Ulrich P.
Kremer, Kyle
Faucher-Giguere, Claude-Andre
Wellons, Sarah
High Energy Astrophysical Phenomena
Cosmology and Nongalactic Astrophysics
Astrophysics of Galaxies
Plasma Physics
Space Physics
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 (SMBHs) down to a few hundred gravitational radii. These 'flux-frozen' and hyper-magnetized disks appear to be qualitatively distinct from classical $α$ disks and magnetically-arrested disks: the midplane pressure is dominated by toroidal magnetic fields with plasma $β\ll 1$ powered by advection of magnetic flux from the interstellar medium (ISM), and they are super-sonically and trans-Alfvenically turbulent with cooling times short compared to dynamical times yet remain gravitationally stable owing to magnetic support. In this paper, we present a simple analytic similarity model for such disks. For reasonable assumptions, the model is entirely specified by the boundary conditions (inflow rate at the BH radius of influence [BHROI]). We show that the scalings from this model are robust to various detailed assumptions, agree remarkably well with the simulations (given their simplicity), and demonstrate the self-consistency and gravitational stability of such disks even in the outer accretion disk (approaching the BHROI) at hyper-Eddington accretion rates.
title An Analytic Model For Magnetically-Dominated Accretion Disks
topic High Energy Astrophysical Phenomena
Cosmology and Nongalactic Astrophysics
Astrophysics of Galaxies
Plasma Physics
Space Physics
url https://arxiv.org/abs/2310.04507