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M. Bershady (University of Wisconsin-Madison)
Our optical-near-infrared view of the distant universe strongly favors identifying the blue, high surface-brightness knots of gas-rich mergers. The deepest measured field merger rate is from the Hubble Deep Field NICMOS data. We explore the extent to which such data give us a merger inventory of the comoving galaxy population of today's luminous galaxies. At one extreme, identifying the high redshift counterparts of the cold spiral disks embedded today in massive halos are of interest because these galaxies are unlikely to have undergone major mergers within the last 5-10 Gyr. At the other extreme, it is important to test whether the merger rate's dependence on cosmic epoch, environment, and mass (today) drives ``down-sizing" of star-formation sites with redshift. In this context it may appear reasonable to connect Lyman Break galaxies at high redshift, the luminous, blue compact galaxies found at intermediate redshift, and HII galaxies at low redshift. Missing, however, is a direct measurement of mass for most of these systems. We briefly comment on the most pressing needs for future observations.