Date/Time
Date(s) - 26/05/2004
3:30 pm - 4:30 pm

Title: The Quenching of Galaxy Formation by Quasar Outflows

Speaker: Dr. Evan Scannapieco

Institute: Kavli Institute for Theoretical Physics
UCSB

Location: ABB 102

Description:

In the heart of each galaxy lies a black-hole, millions of times more massive than the Sun. While most of these objects are now quiescent, their birth was marked by a fantastic explosion of light and kinetic energy, known as a quasar. Thus the centers of newly-formed galaxies once shone with luminosities greater than 10^12 stars and drove out jets of material with velocities of thousands of kilometers per second. As these outflows made their way into the diffuse intergalactic medium, large regions were shock-heated above a critical entropy. At this point cooling became impossible within them, regardless of density, and the formation of new galaxies was quenched completely. This quenching explains three conspicuous observational features that are otherwise completely mysterious: the fall-off in the number of quasars at late times, the characteristic maximum size of galaxies, and the anomalous entropy levels of the “intracluster” gas that permeates galaxy clusters.