TURBULENT STRESSES IN LOCAL SIMULATIONS OF RADIATION-DOMINATED ACCRETION DISKS, AND THE POSSIBILITY OF THE LIGHTMAN-EARDLEY INSTABILITY
- Institute for Research on Earth Evolution, JAMSTEC, Yokohama, Kanagawa 236-0001 (Japan)
- Department of Physics, University of California, Santa Barbara, CA 93106 (United States)
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States)
We present the results of a series of radiation MHD simulations of a local patch of an accretion disk, with a fixed vertical gravity profile but with different surface mass densities and a broad range of radiation to gas pressure ratios. Each simulation achieves a thermal equilibrium that lasts for many cooling times. After averaging over times that are long compared to a cooling time, we find that the vertically integrated stress is approximately proportional to the vertically averaged total thermal (gas plus radiation) pressure. We map out-for the first time on the basis of explicit physics-the thermal equilibrium relation between stress and surface density: the stress decreases (increases) with increasing surface mass density when the simulation is radiation (gas) pressure dominated. The dependence of stress on surface mass density in the radiation pressure dominated regime suggests the possibility of a Lightman-Eardley inflow instability, but global simulations or shearing box simulations with much wider radial boxes will be necessary to confirm this and determine its nonlinear behavior.
- OSTI ID:
- 21367383
- Journal Information:
- Astrophysical Journal, Vol. 704, Issue 1; Other Information: DOI: 10.1088/0004-637X/704/1/781; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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