Paper detail

A catalogue of galaxy cluster models

We present a technique to construct a fair sample of simulated galaxy clusters, and build such a sample for a specific cosmological structure formation scenario. Conventionally one extracts such a sample from a single low-resolution large-scale simulation. Here we simulate the clusters individually at high resolution. We construct a model catalogue selected on expected final cluster mass. Such a catalogue will not have a well-defined richness limit, because the relation between richness and mass is fairly broad. However, by applying the appropriate completeness corrections, the results for the mass-selected catalogue can be compared with observations for richness-selected cluster catalogues. We build a model cluster catalogue for the Omega_0=1 CDM scenario that is designed to mimic the ENACS sample of rich Abell clusters. We use the distribution of richness, corrected for incompleteness, to fix the present epoch. We find sigma_8=0.4-0.5, which is consistent with other determinations. The catalogue is 70 per cent complete for a richness larger than 50, but we do have a complete subsample for a richness limit of 75. As a first test we compare the cumulative distribution of line-of-sight velocity dispersions to those found for several observational samples, and find that they match best for a value of around 0.4 for sigma_8. This means that we find consistent values for sigma_8 for the CDM Omega_0=1 scenario on cluster scales.