Astronomy Colloquium / Fall 2006

September 27

Pr. Charles Gammie

Univ. of Illinois & Inst. for Advanced Study

Urbana Champaign & Princeton

Numerical Models of Black Hole Accretion Flows

Relativistic, magnetized plasmas near black holes are believed to power some of the most luminous objects in the universe, including quasars and gamma-ray bursts. I will review the state of the art in numerical modeling of these flows, which place familiar physics-- hydrodynamics-- in an unusual setting. To date most multidimensional time-dependent numerical models have assumed that the near-horizon plasma is nonradiative. This is appropriate for weakly radiating flows such as the galactic center (Sgr A*), but limits the ability of the models to make contact with observations. I will discuss recent efforts to incorporate radiative effects numerically and discuss the prospects for using astronomical observations to test the underlying gravitational physics.