Infrared Views of Galaxy Evolution: A Progress Report

The two major functions in galaxy evolution that we would like to measure are the stellar populations in galaxies, and their time-derivative, the star formation rate. Especially at redshifts above 1, both of these measures are benefiting greatly from wide-area infrared data. To date, most of these infrared observations suggest that a significant fraction of the star formation suffers substantial internal extinction from dust. Ground-based illustrations include optical/infrared photometric redshift estimates of Balmer-break galaxies, and near-infrared narrow-band imaging and spectroscopy of emission lines redshifted from the optical rest frame. Space-based examples include slitless spectroscopic surveys for H-alpha line emission, mid- and far-infrared diffuse background measurements and deep number counts, and searches for starlight from damped Lyman-alpha absorbers.