Galaxy Clustering Evolution in the CNOC2 High-Luminosity Sample

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Abstract
The redshift evolution of the galaxy two-point correlation function is a fundamental cosmological statistic. To identify similar galaxy populations at different redshifts, we select a strict volume-limited sample culled from the 6100 cataloged CNOC2 galaxies. Our high-luminosity subsample selects galaxies having k-corrected and evolution-compensated R luminosities, M_R^{k,e}, above -20 mag (H_0=100 km/s/Mpc) where M_ast^{k,e}(R)simeq -20.3 mag. This subsample contains about 2300 galaxies distributed between redshifts 0.1 and 0.65 spread over a total of 1.55 square degrees of sky. A similarly defined low-redshift sample is drawn from the Las Campanas Redshift Survey. We find that the co-moving two-point correlation function can be described as xi(r|z) = (r_00/r)^gamma (1+z)^{-(3+epsilon-gamma)} with r_{00}=5.03+/-0.08/h Mpc, epsilon=-0.17+/- 0.18 and gamma=1.87+/-0.07 over the z=0.03 to 0.65 redshift range, for Omega_M=0.2, Lambda=0. The measured clustering amplitude and its evolution are dependent on the adopted cosmology. The measured evolution rates for Omega_M=1 and flat Omega_M=0.2 background cosmologies are epsilon=0.80+/-0.22 and epsilon=-0.81+/-0.19, respectively, with r_{00} of 5.30+/-0.1/h Mpc and 4.85+/-0.1/h Mpc, respectively. The sensitivity of the derived correlations to the evolution corrections and details of the measurements is presented. The analytic prediction of biased clustering evolution for only the low density, LambdaCDM cosmology is readily consistent with the observations, with biased clustering in an open cosmology somewhat marginally excluded and a biased Omega_M=1 model predicting clustering evolution that is more than 6 standard deviations from the measured value.

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