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

Eighteen candidates for emission-line galaxies were discovered in a narrowband infrared survey that targeted the redshifts of damped Ly alpha or metal lines in the spectra of quasars. The presence of emission lines is inferred from the photometric magnitudes in narrowband and broadband interference filters, corresponding to H alpha at redshifts of 0.89 (six objects) and 2.4 (10 objects) and to [O II] lambda 3727 at a redshift of 2.3 (two objects). Most of the candidates are small, resolved objects that are compatible with galaxies at the redshifts of the damped Ly alpha 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 a formation within filaments or sheets whose locations are indicated by the redshifts of strong Ly alpha line absorption along the lines of sight to more distant quasars.