Strong Spatial Clustering of Ultraviolet-selected Galaxies with Magnitude K s < 20.5 and Redshift z ~ 2

Abstract

We obtained deep 8.5m×8.5m near-infrared (IR) images within four high-redshift survey fields, measured the Ks magnitudes of 300 optically selected galaxies with spectroscopic redshift 1.8 <20.5 and Ks>20.5. We found at greater than 95% confidence that the brighter galaxies cluster more strongly. The best-fit correlation lengths for the bright and faint samples are 10+/-3 and 4+/-0.8 h-1 comoving Mpc, respectively (1 σ), although the unusual density of bright QSOs in one of our survey fields may imply that the result is not representative of the universe as a whole. Neglecting this possibility, the correlation length for the optically selected sample with Ks<20.5 agrees well with that reported for comparably bright near-IR-selected samples. The differences in correlation length between optically selected and near-IR-selected samples have been presented as evidence that the two techniques find orthogonal populations of high-redshift galaxies. Our results favor a more nuanced view. Based, in part, on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership between the California Institute of Technology, the University of California, and NASA, and was made possible by the generous financial support of the W. M. Keck Foundation.