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Author Hirabayashi, Kota ♦ Hoshino, Masahiro
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword ASTROPHYSICS, COSMOLOGY AND ASTRONOMY ♦ ACCRETION DISKS ♦ ADVECTION ♦ AMPLITUDES ♦ ANGULAR MOMENTUM ♦ ANISOTROPY ♦ BLACK HOLES ♦ COMPARATIVE EVALUATIONS ♦ EFFICIENCY ♦ INSTABILITY ♦ MAGNETIC FIELDS ♦ MAGNETIC RECONNECTION ♦ MAGNETOHYDRODYNAMICS ♦ RELATIVISTIC RANGE ♦ ROTATION ♦ SIMULATION ♦ TURBULENCE
Abstract This paper presents a series of stratified-shearing-box simulations of collisionless accretion disks in the recently developed framework of kinetic magnetohydrodynamics (MHD), which can handle finite non-gyrotropy of a pressure tensor. Although a fully kinetic simulation predicted a more efficient angular-momentum transport in collisionless disks than in the standard MHD regime, the enhanced transport has not been observed in past kinetic-MHD approaches to gyrotropic pressure anisotropy. For the purpose of investigating this missing link between the fully kinetic and MHD treatments, this paper explores the role of non-gyrotropic pressure and makes the first attempt to incorporate certain collisionless effects into disk-scale, stratified disk simulations. When the timescale of gyrotropization was longer than, or comparable to, the disk-rotation frequency of the orbit, we found that the finite non-gyrotropy selectively remaining in the vicinity of current sheets contributes to suppressing magnetic reconnection in the shearing-box system. This leads to increases both in the saturated amplitude of the MHD turbulence driven by magnetorotational instabilities and in the resultant efficiency of angular-momentum transport. Our results seem to favor the fast advection of magnetic fields toward the rotation axis of a central object, which is required to launch an ultra-relativistic jet from a black hole accretion system in, for example, a magnetically arrested disk state.
ISSN 0004637X
Educational Use Research
Learning Resource Type Article
Publisher Date 2017-06-10
Publisher Place United States
Journal Astrophysical Journal
Volume Number 842
Issue Number 1


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