3 May 2007

Speaker: Mike Shull (University of Colorado)

Title:Search for the Missing Baryons

Abstract: From models of light-element nucleosynthesis (D/H) and acoustic peaks in the cosmic microwave background (CMB), astronomers now believe that ordinary matter (baryons) constitutes approximately 4.5% of the total mass-energy in the universe. But where are these baryons? Only 10% reside in galaxies, with the remainder spread throughout the vast reservoir of the intergalactic medium (IGM). I will describe ultraviolet (Hubble, FUSE) observations of intergalactic Lyman-alpha and selected heavy elements (O VI, C III, C IV, Si III, Si IV, N V) that greatly improve this low-z baryon inventory. In the low-redshift universe, we are just beginning to understand processes of gaseous infall to galaxies and the feedback of winds, radiation, and heavy elements that connect the collapsed forms of matter with the IGM.

Video of the Presentation (Talks can be viewed with RealPlayer. Free download is available from www.real.com )