Imaging of Two Damped Lyman Alpha Absorbers at Intermediate Redshifts

Abstract

By observing the fields of the QSOs 3C 286 and PKS 1229-021 in the I and K_s_ bands under good seeing conditions, we have resolved faint galaxy images close to the QSO sight lines. The sizes, magnitudes, and colors of these objects suggest that they are the galaxies producing 21 cm absorption at z_abs_ = 0.6922 and 0.3950 in the spectra of 3C 286 and PKS 1229-021, respectively. The absorber in front of 3C 286 appears to be a low surface brightness galaxy; this finding provides a natural explanation for the low metallicity and lack of molecular gas in this system at an epoch when the Milky Way had already reached near-solar abundances. The galaxy we identify as the z_abs_ = 0.3950 absorber in PKS 1229-021 is close to the position previously inferred from the character of the metal line absorption and Faraday rotation. In this field we also find several very red objects which we suspect to be elliptical galaxies in a group or cluster at z = 1.042, the redshift of the QSO.