Clustering of K-selected galaxies at 2 < z < 3.5: Evidence for a color-density relation

We study the clustering properties of K-selected galaxies at 2 < z < 3.5 using deep multiwavelength imaging in three fields from the MUSYC survey. These are the first measurements to probe the spatial correlation function of K-selected galaxies in this redshift range on large scales, allowing for robust conclusions about the dark matter halos that host these galaxies. The K-selected galaxies with K < 21 have a correlation length r₀ ∼ 6 h ^-1 Mpc, larger than typical values found for optically selected galaxies. The correlation length does not depend on K-band magnitude in our sample but does increase strongly with color; the J - K > 2.3. distant red galaxies (DRGs) have r₀ ∼ 11 h^-1 Mpc. Furthermore, contrary to findings for optically selected galaxies, K-selected galaxies that are faint in the R band cluster more strongly than brighter galaxies. These results suggest that a color-density relation was in place at z > 2; it will be interesting to see whether this relation is driven by galaxies with old stellar populations or by dusty star-forming galaxies. Irrespective of the cause, our results indicate that K-bright blue galaxies and K-bright red galaxies are fundamentally different, having different clustering properties. Using a simple model of one galaxy per halo, we infer halo masses ∼5 × 10¹² M_⊙ for K < 21 galaxies and ∼2 × 10¹³ M_⊙ for DRGs. A comparison of the observed space density of DRGs to that of their host halos suggests large halo occupation numbers; however, this result conflicts with the lack of a strong small-scale excess in the angular correlation function. Using the predicted evolution of halo mass to investigate relationships between galaxy populations at different redshifts, we find that the z = 0 descendants of the galaxies considered here reside primarily in groups and clusters.