Tracing Cosmic Evolution with an XMM Serendipitous Cluster Survey.

This paper describes updated predictions, as a function of the underlying cosmological model, for a serendipitous galaxy cluster survey that we plan to conduct with the {\em XMM-Newton} X-ray Satellite. We have included the effects of the higher than anticipated internal background count rates and have expanded our predictions to include clusters detected at 3 sigma. Even with the enhanced background levels, we expect the XCS to detect sufficient clusters at z>1 to differentiate between open and flat cosmological models. We have compared the XCS cluster redshift distribution to those expected from the XMM Slew Survey and the ROSAT Massive Cluster Survey (MACS) and find them to be complementary. We conclude that the future existence of the XCS should not deter the launch of a dedicated X-ray survey satellite.