THE CLUSTERING PROPERTIES OF FAINT GALAXIES

The two-point angular correlation function of galaxies, w(theta), has been computed from a new survey of faint galaxies covering a 2 deg(2) area near the north galactic pole. This survey, which is complete to l imiting magnitudes J = 24 and F = 23, samples angular scares as large as 1.degrees 5. Faint galaxies are found to be more weakly clustered ( by a factor of at least 2) compared to galaxies observed locally. Clus tering amplitudes are closer to model predictions in the red than in t he blue. The weak clustering of faint galaxies cannot be explained by any plausible model of clustering evolution with redshift. However, on e possible explanation of the clustering properties of intermediate-re dshift galaxies is that they resemble those of starburst galaxies and H II region galaxies, which are observed locally to possess weak clust ering amplitudes. Our clustering amplitudes are also similar to those of nearby late-type galaxies, which are observed to be more weakly clu stered than early-type galaxies. A simple, self-consistent model is pr esented that predicts the fraction of galaxies in the ''excess'' popul ation at intermediate redshifts and correctly matches observed color d istributions. The available data on the clustering properties of faint galaxies are consistent with this model if the ''excess'' population of faint blue galaxies is also the weakly clustered population. Eviden ce is presented that the power-law slope of the angular correlation fu nction becomes shallower at fainter magnitudes. A similar effect is se en locally both for dwarf galaxies and for galaxies with late morpholo gical type; this effect is roughly consistent with the model.