CfA Colloquium: September 12, 2002

Speaker: John Hawley (U. Virginia)

Title: 3D Simulations of Magnetic Accretion Disks: Local to Global

Abstract: Observations are providing increasingly detailed quantitative information about the accretion flows that power such high energy systems as X-ray binaries and Active Galactic Nuclei. These observations have been modeled in some detail by a variety of accretion scenarios, but such models must rely on assumptions such as regular flow geometry and a simple, parameterized stress. It is now known that magnetic fields are of fundamental importance for the structure and evolution of accretion disks. Magnetic turbulence is almost certainly the source of anomalous stress in accretion disks. Numerical MHD simulations offer a way to investigate the basic physical dynamics of accretion flows self-consistently. In this talk I will review the development of these simulations, from local to global models. I will focus on two recent applications: (1) underluminous (``non-radiating'') accretion flows, of which the Galactic Center is the best known example, and (2) the structure and dynamics of the inner edge of accretion disks around black holes.

Reference for students:
Balbus and Hawley, 2002, astro-ph/203353