The Spatial Clustering of Star‐forming Galaxies at Redshifts 1.4 ≲z≲ 3.5

Abstract

We analyzed the spatial distribution of 28,500 photometrically selected galaxies with magnitude 23.5 < AB < 25.5 and redshift 1.4 < z < 3.5 in 21 fields with a total area of 0.81 deg 2 . The galaxies were divided into three subsamples, with mean redshifts = 1.7, 2.2, and 2.9, according to their U n G colors. Combining the galaxies' measured angular clustering with redshift distributions inferred from 1600 spectroscopic redshifts, we find comoving correlation lengths at the three redshifts of r 0 = 4.5 ± 0.6, 4.2 ± 0.5, and 4.0 ± 0.6 h -1 Mpc, respectively, and infer a roughly constant correlation function slope of γ = 1.6 ± 0.1. We derive similar numbers from the 1600 object spectroscopic sample itself with a new statistic, K , that is insensitive to many possible systematics. Galaxies that are bright in (λ rest ~ 1500-2500 Å) cluster more strongly than fainter galaxies at z = 2.9 and 2.2 but not, apparently, at z = 1.7. Comparison to a numerical simulation that is consistent with recent WMAP observations suggests that galaxies in our samples are associated with dark matter halos of mass 10 11.2 -10 11.8 ( z = 2.9), 10 11.8 -10 12.2 ( z = 2.2), and 10 11.9 -10 12.3 M ☉ ( z = 1.7) and that a small fraction of the halos contain more than one galaxy that satisfies our selection criteria. Adding recent observations of galaxy clustering at z ~ 0 and ~1 to the simulation results, we conclude that the typical object in our samples will evolve into an elliptical galaxy by redshift z = 0 and will already have an early-type spectrum by redshift z = 1. We comment briefly on the implied relationship between galaxies in our survey and those selected with other techniques.