Global Radiation MHD Simulations of Black Hole Accretion Disks
Thu, April 21, 2016
The inner regions of accretion flows in luminous sources such as AGN and X-ray binaries are radiation dominated. In the case of AGN, radiation and winds produced by such flows are thought to be an important feedback mechanism during galaxy formation in massive halos. I present new results from numerical studies of the magnetohydrodynamics of accretion this regime. These calculations use numerical methods based on a formal solution of the time-dependent radiation transfer equation, eliminating the need for approximate closures. We find that turbulent transport of radiation energy can be a significant contribution to the cooling rate in the disk, and this changes the global properties of the flow compared to standard slim-disk models. We describe new work to extend our calculations to full general relativity, in order to follow the dynamics in the innermost regions of the disk.