Joint Astrophysics Colloquium

Staring into the Abyss: Imaging Black Hole Horizons

Avery Broderick

CITA

Millimeter VLBI has become a reality and sub-millimeter VLBI will be feasible in the very near future. These techniques make possible the imaging of the black hole horizons of at least two supermassive black holes, those lying at the centers of the Milky Way and M87. Already results have been obtained that have importance for fundamental gravitational physics: whether or not black hole horizons exist. Future measurements promise to test whether or not the Kerr metric is an adequate description of strong gravity in the vicinity of supermassive black holes. In addition, these observations are being brought to bear upon unresolved astrophysical questions surrounding black hole accretion and outflows, providing critical empirical input into jet-formation physics and the inner structure of black hole accretion flows. I will discuss how these measurements are being made, how they may be optimized in the near future using existing observatories, what we expect to see and how they may be used to address fundamental questions in black hole science.