Astronomy Colloquium

Supermassive black holes, long suspected of driving nuclear activity in quasar-like objects, reside at the centers of most, if not all, massive galaxies. Methods by which their masses are measured, such as modeling of stellar or gas dynamics on resolvable scales, are difficult or impossible to use when there is an active nucleus present. However, in the case of active galaxies, the central mass can be measured by the process of reverberation mapping. The time-delayed response of the broad emission lines to continuum flux variations allows us to determine the size of the line-emitting region, and the mass of the central object is obtained by combining the size with the Doppler-broadened line width. In this talk, I will outline the fundamentals of reverberation mapping and black hole mass measurement and show how these anchor simple scaling relationships that allow us to easily estimate black hole masses for large samples of quasars.