Title:

The Nature of Nonradiaitve, Magnetized Accretion onto Sgr A*


Chris Matzner
Canadian Institute for Theoretical Astrophysics

Abstract:

The supermassive black hole at the center of the Milky Way is vastly
underluminous compared to simple estimates.  After reviewing observations
and theory of the Sgr A* environment I will describe a program of
three-dimensional MHD simulations meant to elucidate the dynamics of the
inflow.  (These include some of the largest MHD simulations ever
performed.)  Unexpectedly, these simulations reveal the growth of a
stagnant, superadiabatic atmosphere best described as a state of
"magnetically-frustrated convection", in which both the inflow rate and
the radiative efficiency are strongly reduced.  I will contrast this state
with previous suggestions, discuss its implications, and touch on some
caveats about it.