http://stream.publicbroadcasting.net/production/mp3/wamc/local-wamc-986195.mp3
Albany, NY – In today's Academic Minute, Dr. Chris Impey of the University of Arizona explores ancient light in an effort to better understand the lifecycle of supermassive black holes.
Chris Impey is a University Distinguished Professor and Deputy Head of the Department of Astronomy at the University of Arizona where his research interests include observational cosmology, gravitational lensing, and the evolution and structure of galaxies. He has authored 160 refereed publications and more than thirty popular articles on cosmology and astrobiology. He holds a Ph.D. from the University of Edinburgh.
Dr. Chris Impey - Supermassive Black Holes
Black holes have gone from exotic to mundane. They're thought to be the super-compact end state of rare massive stars, so dense that nothing can escape, not even light. But over the past few decades, astronomers have learned that our galaxy, and every galaxy we've inspected carefully, has a super-massive black hole in its center. The Milky Way has a modest one, just a few million times the Sun's mass. But in some galaxies nature can create dark beasts a billion times more massive than the Sun.
My research focuses on explaining the evolution of supermassive black holes and their surrounding galaxies. In the modern view of cosmology, galaxies grow by mergers and acquisitions. For example, the Milky Way was assembled from hundreds of smaller galaxies over ten billion years. Even today we see signs that our galaxy has recently eaten some small galaxies. Its big meals were long ago; now it's just snacking.
The black hole at the center of a galaxy also grows over cosmic time. It eats gas and swallows stars whole, and when it's eating and growing, it accelerates particles and shines brightly at all wavelengths. We call that a quasar. But between meals the supermassive black hole can be quiet and dark. The black hole in our galaxy is quiescent. If it were active it would be bright enough to see in the daytime sky.
I use a large telescope in Chile to take data on hundreds of galaxies and their central black holes. I weigh the black holes and the galaxies and see whether or not the black holes are active and growing. In the early universe nobody knows which came first, the galaxy or the black hole, and nobody knows how fast the black holes grew. I'm trying to figure that out by using a telescope as a time machine to gather ancient light.