Published in "Extragalactic Background Radiation", Space Telescope Science Institute Symposium Series 7, 1995, eds. D. Calzetti, M. Livio and P. Madau
Abstract. The extragalactic night sky is filled with the light from stellar formation and heavy element production integrated back to the epoch of maximum quasar density. This is a review of the status of our understanding of the faint blue galaxies and the extragalactic background light (EBL) from 0.15 to 2.3 µm. New data on faint galaxies and the EBL are also presented. Ultra deep CCD imaging surveys have revealed a population of faint blue galaxies covering the sky. To a surface brightness of 29 B mag arcsec-2 there are about 100 background galaxies per square arcminute anywhere in the sky. These 25-27 magnitude galaxies are apparently distributed over a broad redshift range of 1-3. A gravitational lens test of the redshift distribution of these galaxies also implies that most of them lie beyond redshift 0.7. Although measured redshifts of galaxies grow monotonically with magnitude, there may be several populations of galaxies at redshifts greater than 0.5; there is evidence that the mix of types is different at high and low redshift. The data do not require galaxy number non-conservation, and a variety of models of stellar population evolution are consistent with the data. Studies of the angular correlations of faint galaxies show a red/blue effect and very little clustering in faint blue galaxies. The seeing-deconvolved half light radii of these galaxies approach 0.8 arcsecond at the faint end.
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