Scientific Seminars

The Evolution of Galaxies since z=1

Alan Dressler
Carnegie Observatory (USA)

2006-10-25    14:00    Brera -

The universe of galaxies we are familiar with appeared around z~1. Since that time, the specific star formation rate has declined rapidly and the number of galaxies on the "red sequence" has grown. There is evidence that the population of S0 galaxies has grown since z=1 at the expense of a class of spiral galaxies that no longer exists. Elliptical galaxies appear to be "full grown" in clusters at z=1, but some studies suggest that their counterparts in lower-density groups and the field continue to grown through so-called "dry mergers." Starburst appears to have been the preferred mode of star formation at z = 1, but star formation has decayed to a constant trickle for most galaxies today, perhaps due to declining gas reserves amidst a sea of unavailable baryons. Studying these evolutionary processes are as important as the birth processes of galaxies to understand how the galaxies of today came to be.