Discovery of a Galaxy Responsible for a DLA System at z = 3.15 and a Near-Infrared Search for Primeval Galaxies

We report the detection, both in line and continuum emission, of a galaxy responsible for a damped Lyα absorption (DLA) system at z = 3.15 projected 2.3 from QSO 2233+131. The star formation rate implied by both the Lyα and restframe far-UV continuum is ∼ 7 M⊙ yr . The galaxy also shows no sign of an active nucleus and has blue colors, both consistent with it being observed early in its star formation history. The Lyα emission is offset ∼ 200 km s from the DLA velocity, which could be explained as the rotational signature of a disk galaxy. We also report on the progress of an ongoing near-infrared narrowband search with the Keck telescope for line emission from a population of primeval galaxies at high redshift. We have found several promising candidates which are being followed up with optical spectroscopy. Our survey is beginning to place constraints on a possible population of slightly dusty primeval galaxies at high redshift. 1. Discovery of the Galaxy Responsible for DLA 2233+131 Damped Lyman-alpha absorber (DLA) systems, detected along lines of sight to unrelated high-redshift quasars, have been proposed as possible progenitors of normal disk galaxies today. They appear to contain a substantial fraction of the baryons known to exist in normal galaxies today (Lanzetta, Wolfe, & Turnshek 1995). Several searches for the galaxies responsible for various DLA systems have resulted in a few detections of emission–line galaxies (Lowenthal et al. 1991; Macchetto et al. 1993; Møller & Warren 1993; Francis et al. 1996), but all appear either to be AGN or are at a similar redshift as the QSO, suggesting that the source of their ionization may not be a result of star formation. We report on the detection of an object, designated DLA 2233+131, responsible for a previously known DLA system at zabs = 3.150 (Lu et al. 1993) in the spectrum of QSO 2233+131 (zQSO = 3.295; Crampton, Schade, & Cowley