Astronomy 162 - Stars, Galaxies, & The Universe

What are Active Galaxies and Quasars? We have good reason to think that buried deep in the hearts of nearly every (?) bright galaxy is a supermassive black hole with masses of millions or even billions of times the mass of the Sun. Most, like the one in our Milky Way, are quiescent, but in about 1% of galaxies, they are fed enough matter (up to about a sun's worth per year), and light up as an Active Galactic Nucleus (AGN) that can outshine an entire galaxy full of billions of stars. This lecture reviews the observed properties of Active Galaxies, the riddle of the Quasars, and the recognition that they are powered by the accretion of matter onto supermassive black holes. The lecture ends with some open questions in this active area of current research. Recorded 2006 February 16 in 1008 Evans Laboratory on the Columbus campus of The Ohio State University.