Infrared emission-line galaxies associated with damped Lyman-alpha and strong metal absorber redshifts

Abstract

Eighteen candidates for emission line galaxies were discovered in a narrow-band infrared survey that targeted the redshifts of damped Lyman-alpha or metal lines in the spectra of quasars. The presence of emission lines is inferred from the photometric magnitudes in narrow and broad band interference filters, corresponding to H-alpha at redshifts of 0.89 (6 objects) and 2.4 (10 objects), and [OII] at a redshift of 2.3 (2 objects). Most of the candidates are small resolved objects, compatible with galaxies at the redshifts of the absorbers. Because a similar survey targeted at the redshifts of quasars themselves uncovered only one emission-line galaxy in a larger volume, the results imply substantial clustering of young galaxies or formation within filaments or sheets whose locations are indicated by the redshifts of strong absorption along the lines of sight to more distant quasars.