PRIMUS: Galaxy Clustering as a Function of Luminosity and Color at 0.2

Publication information:

Skibba R, Smith S, Coil A, Moustakas J, Aird J, Blanton M, Bray A, Cool R, Eisenstein D, Mendez A, et al. PRIMUS: Galaxy Clustering as a Function of Luminosity and Color at 0.2. ArXiv e-prints. 2013;1310:1093.

Abstract

We present measurements of the luminosity and color-dependence of galaxyclustering at 0.21.0 in the PRIsm MUlti-object Survey (PRIMUS).We quantify the clustering with the redshift-space and projectedtwo-point correlation functions, xi(rp,pi) and wp(rp), usingvolume-limited samples constructed from a parent sample of over 130,000galaxies with robust redshifts in seven independent fields covering 9sq. deg. of sky. We quantify how the scale-dependent clusteringamplitude increases with increasing luminosity and redder color, withrelatively small errors over large volumes. We find that red galaxieshave stronger small-scale (0.11 Mpc/h) clustering and steepercorrelation functions compared to blue galaxies, as well as a strongcolor dependent clustering within the red sequence alone. We interpretour measured clustering trends in terms of galaxy bias and obtain valuesbetween b_gal=0.9-2.5, quantifying how galaxies are biased tracers ofdark matter depending on their luminosity and color. We also interpretthe color dependence with mock catalogs, and find that the clustering ofblue galaxies is nearly constant with color, while redder galaxies havestronger clustering in the one-halo term due to a higher satellitegalaxy fraction. In addition, we measure the evolution of the clusteringstrength and bias, and we do not detect statistically significantdepartures from passive evolution. We argue that the luminosity- andcolor-environment (or halo mass) relations of galaxies have notsignificantly evolved since z=1. Finally, using jackknife subsamplingmethods, we find that sampling fluctuations are important and that theCOSMOS field is generally an outlier, due to having more overdensestructures than other fields; we find that 'cosmic variance' can be asignificant source of uncertainty for high-redshift clusteringmeasurements.