Advection-Dominated Accretion around Black Holes
  This article reviews the physics of advection-dominated accretion flows (ADAFs) and describes applications to several black hole X-ray binaries and galactic nuclei. The possibility of using ADAFs to explore the event horizons of black holes is highlighted. 
Ramesh Narayan, Rohan Mahadevan, and Eliot Quataert (Harvard)