"Searching Between the Galaxies: Missing Baryons in the Intergalactic Medium"
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
4.6% 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 IGM observations in the ultraviolet and
X-ray, together with theoretical models, that attempt to reconcile
this "baryon inventory". In the low-redshift universe, we are
just beginning to understand processes of galaxy formation and the
feedback of winds, radiation, and heavy elements that connect the
collapsed forms of matter with the IGM.