Cosmology

Abstract:

We predict the errors on counts-in-cells statistics measured in the future VIRMOS survey. Several effects are included, such as variation of clustering, biasing, and geometry. Most importantly for the survey strategy, sparse sampling appears to have no particular advantage in this case, especially for higher order statistics at high redshift. The predicted accuracy is a few percent for the variance, and about 10 percent for the skewness at z = 1 in a small dynamic range around 1 h(-1) Mpc.

Abstract:

We use three samples (3CRR, 6CE and 6C*) to investigate the radio luminosity function (RLF) for the 'most powerful' low-frequency selected radio sources. We find that the data are well fitted by a model with a constant ca-moving space density at high redshift as well as by one with a declining co-moving space density above some particular redshift. This behaviour is very similar to that inferred for steep-spectrum radio quasars by Willott et al (1998) in Line with the expectations of Unified Schemes. We conclude that there is as yet no evidence for a 'redshift cutoff' in the co-moving space densities of powerful classical double radio sources, and rule out a art-off at z less than or similar to 2.5.