The effect of formation redshifts on the cluster mass-temperature relation

I employ an ensemble of hydrodynamical simulations and the XSPEC MEKAL emis sion model to reproduce observable spectral and flux-weighted temperatures for 24 clusters. Each cluster is imaged at 16 points in its history, which allows the investigation of evolutionary effects on the mass-temperature re lation. In the zero-redshift scaling relations, I find no evidence for a re lationship between cluster temperature and formation epoch for those cluste rs that acquired 75 per cent of their final mass since a redshift of 0.6. T his result holds for both observable and intrinsic intracluster medium temp eratures, and implies that halo formation epochs are not an important varia ble in analysis of observable cluster temperature functions.