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Effects of finite resistivity on magnetorotational instabilities in a realistic accretion flow

Authors
Journal
New Astronomy
1384-1076
Publisher
Elsevier
Publication Date
Volume
7
Issue
6
Identifiers
DOI: 10.1016/s1384-1076(02)00139-2
Keywords
  • Accretion
  • Accretion Disks
  • Mhd
  • Instabilities
  • Diffusion

Abstract

Abstract A local perturbation analysis is performed on a realistic background accretion flow in a global magnetic field. The adopted background model is an analytic solution to the resistive MHD equations and describes magnetically-controlled advection-dominated accretion flows (ADAFs) with an accuracy to the first order in the resistive corrections. The results show that there are three independent wave modes, which may be called the Rayleigh, Balbus–Hawley and resistive modes. Within our resistive-MHD corrections to the ideal-MHD limit, a Balbus–Hawley-like criterion for the instability of axisymmetric perturbations appears as a consequence of the competition between damping due to magnetic diffusion and excitation due to shear flow. As for non-axisymmetric perturbations, the former two modes are likely to be unstable in the presence of shears because the magnetic diffusion acts as a stabilizer only to axisymmetric perturbations within our approximation.

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