The CNOC2 field galaxy redshift survey

The second Canadian Network for Observational Cosmology ( CNOC) galaxy redshift survey, CNOC2, is designed to investigate the relations between the dramatic evolution of field galaxies and their clustering over the redshift range 0 to 0.7. The sample of about 6000 galaxies with accurate velocities is spread over four sky patches with a total area of about 1.5deg2. Here we report preliminary results based on two of the sky patches and within the redshift range of 0.12 to 0.55. After classifying the galaxy spectral energy distributions relative to non–evolving references, we find that the early and intermediate–type populations can be described with nearly pure luminosity evolution, whereas the late–type population requires nearly pure density evolution. The spatial two–point correlation functions have a strong colour dependence with scale, and a weaker, apparently scale–free, luminosity dependence. The population most likely to be conserved with redshift is the high–luminosity galaxies. In particular, we choose galaxies with MRke ⩽−20 mag as our tracer population. We find that the evolution of the clustered density in proper co–ordinates at r ≲ 10h−1 Mpc, ρgg ∝ r0γ(1+z)3, is best described as a ‘de–clustering’, proportional to (1+z)0.6±0.4); or equivalently, there is a weak growth of clustering in co–moving co–ordinates, x0 ∝(1+z)(−0.3±0.2). This conclusion is supported by the pairwise peculiar velocities, which show no significant change with redshift. The cosmic virial theorem applied to the CNOC2 data gives Q3ΩM/b = 0.11 ± 0.04, where Q3 is the three–point correlation parameter and b the bias.