Systematic effects in the interpretations of Cluster X-ray Temperature functions

Abstract

The formation and evolution of clusters of galaxies are sensitive to the underlying cosmological model. Constraints on cosmological parameters of cold dark matter models have been derived from mass, temperature and luminosity functions of clusters. We study the importance of including cluster formation history and a correction for collapsed fraction of objects in determining the cluster X-ray temperature function. We find that both effects are important. We compare temperature functions obtained by using a power law approximation for the mass variance normalized to X-ray clusters to those obtained by using a COBE normalized full CDM treatment. We conclude that the temperature function could be a powerful test on the average density of the Universe if we could find the correct way of interpreting the data.