Growth of the MRI in Accretion Discs -- the Influence of Radiation Transport

Abstract

In this paper we investigate the influence of radiative transport on the growth of the magnetorotational instability (MRI) in accretion discs. The analysis is performed by use of analytical and numerical means. We provide a general dispersion relation together with the corresponding eigenfunctions describing the growth rates of small disturbances on a homogeneous background shear flow. The dispersion relation includes compressibility and radiative effects in the flux-limited diffusion approximation. By introducing an effective speed of sound, all the effects of radiation transport can be subsumed into one single parameter. It can be shown that the growth rates of the vertical modes -- which are the fastest growing ones -- are reduced by radiative transport. For the case of non-vertical modes, the growth rates may instead be enhanced. We quantify the effects of compressibility and radiative diffusion on the growth rates for the gas-pressure dominated case. The analytical discussion is supplemented by numerical simulations, which are also used for a first investigation of the non-linear stage of the MRI in gas-pressure dominated accretion discs with radiation transport included.

11 pages, 11 figures

References in corpus (9)

• Accretion disc viscosity: how big is alpha?
• MHD simulations of the magnetorotational instability in a shearing box with zero net flux. II. The effect of transport coefficients
• MHD simulations of the magnetorotational instability in a shearing box with zero net flux. I. The issue of convergence
• Migration of Protoplanets in Radiative Disks
• Angular Momentum Transport in Accretion Disks: Scaling Laws in MRI-driven Turbulence
• Global MHD simulations of stratified and turbulent protoplanetary discs. I. Model properties
• An Exact, Three-Dimensional, Time-Dependent Wave Solution in Local Keplerian Flow
• Thermodynamics of an Accretion Disk Annulus with Comparable Radiation and Gas Pressure
• Surface Structure in an Accretion Disk Annulus with Comparable Radiation and Gas Pressure

Cited by in corpus (5)

• Vertical Structure and Turbulent Saturation Level in Fully Radiative Protoplanetary Disc Models
• The CRONOS Code for Astrophysical Magnetohydrodynamics
• Temperature Fluctuations driven by Magnetorotational Instability in Protoplanetary Disks
• Magnetorotational instability in decretion disks of critically rotating stars and the outer structure of Be and Be/X-ray disks
• Magnetic clouds in the solar wind: A numerical assessment study of analytical models