A Glimpse of Field Galaxies at Redshifts Z ~ 1 Using HST and the Keck Telescope

Abstract

Data from the Keck and Hubble Space Telescopes have been combined to explore the nature of very faint I > 22 field galaxies. At a redshift z ~ 1, such galaxies have luminosities similar to that of typical galaxies today. Though small, our sample of 33 redshifts already suggest that the median redshift for I > 22 galaxies is higher than the z = 0.6 expected for the “maximum merger model” of Carlberg (1995). At redshifts z > 0.8, mergers, interactions, and infall of minor galaxies into larger hosts appear to be common events; a wide diversity of morphological types existed; and some stellar populations were already so red that their major formation epoch occurred at redshifts z > 2.