The Luminosity-Temperature Relation at [CLC][ITAL]z[/ITAL][/CLC] = 0.4 for Clusters of Galaxies

Abstract

We have obtained the first large sample of accurate temperatures forclusters at z > 0.14 from ASCA. We compare the luminosity-temperature(L-T) distribution for these clusters with the low-redshift sample ofDavid and coworkers and find that there is no evidence for evolution. Wealso find that the intrinsic variance in this relation is roughlyconstant with redshift. Additionally, there is no detectable change inthe relationship of optical velocity dispersion to X-ray temperaturewith redshift. Most cosmological simulations driven primarily by gravitypredict substantial changes in the L-T relation due to the recent rapidgrowth of clusters. Our results are consistent either with models inwhich the cluster core entropy is dominated by preheating, or with low-Omega models in which cluster structure does not evolve strongly withtime. The intrinsic variance in the L-T relation at a fixed redshift canbe due to variety of possible causes, e.g., a change in the baryonicfraction from cluster to cluster, variation in the fraction of the totalenergy in the system arising from shocks or supernova heating, orvariations in the emission measure distributions in multiphase gas.