CRA seminar: Dr. Yan-Fei Jiang (University of California Santa Barbara)

3D Radiation Magneto-hydrodynamic Simulations of Accretion Disks around
Supermassive Black Holes

Abstract:

Black hole accretion disks convert the gravitational energy of accreted
gas to photons and produce varies observational phenomena of AGNs. First
principle calculations of black hole accretion disks for a wide range of
accretion rates are not only important for understanding various
observational properties of accreting black hole systems, but can also
improve our understanding on the growth of black holes as well as
connections between the central black holes and the host galaxies. I
will describe our recent 3D radiation MHD simulations of accretion disks
when the accretion rate is below the Eddington limit as observed for
most AGNs. Coronae is self-consistently produced above the photosphere
of the disk. Properties of the coronae as a function of mass accretion
rate are also consistent with observations. Structures of the accretion
disks are different from the standard alpha disk model in many ways.
Additional opacity peaks besides electron scattering play an important
role in AGN disks, which can potentially explain the variability of AGNs
over a few years’ time scale, as recently found for the change-look
AGNs. I will also describe how the structures of disk will change when
the accretion rate is above the Eddington-limit.