Jason Dexter (UC Berkeley)

Theory, Simulation and Observation: Piecing Together Black Hole Accretion

Simulations based on the magnetorotational instability provide a first principles physical description of black hole accretion flows, and are starting to be used to interpret observations of astrophysical sources. Most codes neglect radiation, but in low-luminosity systems observables can be calculated from simulations after the fact via ray tracing. I will describe time-dependent, general relativistic radiative models of Sagittarius A* and M87, and their comparison to event horizon scale resolution very long baseline interferometry observations at millimeter wavelengths. I will also address the prospect of detecting the black hole shadow, direct evidence for the existence of an event horizon. In luminous systems such as AGN and the thermal (high/soft) state of X-ray binaries, the comparison is still necessarily indirect. I will discuss some recent progress in understanding these systems both from radiation MHD simulations and multiwavelength quasar microlensing observations.