# Numerical Simulations

A fundamental problem in the physics of astrophysics is the role of magneto-hydrodynamic processes in accretion (for example, onto black holes) and in the generation of relativistic jets. Professors Julian Krolik and Colin Norman are both pursuing this problem, using techniques ranging from large-scale general relativistic MHD simulations to analytic models. Prof. Krolik has numerous ongoing research programs in this area: exploring the interaction between MHD turbulence and radiation forces in accretion flows; using data generated by 3-d general relativistic MHD simulations to predict the emitted spectrum and polarization of light radiated by accreting black holes; unraveling the dynamics of tilted and precessing disks; predicting photon signatures of merging supermassive black holes; and understanding what happens when a star passes by a large black hole and is torn apart by tidal forces.

**Magnetic fieldline structure in both the accretion disk surrounding a black hole and its outflow, superimposed on logarithmic color contours of gas density.**