There is now good evidence that supermassive black holes reside at the centers of most massive galaxies: the difference between active and quiescent galaxies is due to differences in some combination of accretion rate and radiative efficiency. In nearby quiescent and active galaxies, black hole masses can be measured by modeling gas or stellar dynamics, both of which require high angular resolution. However, in active galaxies, masses can also be measured by reverberation-mapping techniques where time resolution can be used as a surrogate for angular resolution. I will discuss measurements of the masses of the central black holes in galaxies and how these can be used to anchor scaling relationships that allow estimates of the black holes in distant quasars, with some emphasis on the current limitations and intrinsic uncertainties of these techniques.
LCO Seminar Series, 6740 Cortona Dr, Suite 102, Goleta, CA93117