Observational constraints on the redshift evolution of X-ray scaling relations of galaxy clusters out to z  ~  1.5^⋆

Max-Planck-Institut für extraterrestrische Physik, 85748 Garching, Germany
e-mail: hxb@mpe.mpg.de

Received: 9 March 2011
Accepted: 26 July 2011

Abstract

Context. A precise understanding of the relations between observable X-ray properties of galaxy clusters and cluster mass is a vital part of the application of X-ray galaxy cluster surveys to test cosmological models. An understanding of how these relations evolve with redshift is just emerging from a number of observational data sets.

Aims. The current literature provides a diverse and inhomogeneous picture of scaling relation evolution. We attempt to transform these results and the data on recently discovered distant clusters into an updated and consistent framework, and provide an overall view of scaling relation evolution from the combined data sets.

Methods. We study in particular the most important scaling relations connecting X-ray luminosity, temperature, and cluster mass (M–T, L_X–T, and M–L_X) combining 14 published data sets supplemented with recently published data of distant clusters and new results from follow-up observations of the XMM-Newton Distant Cluster Project (XDCP) that adds new leverage to efficiently constrain the scaling relations at high redshift.

Results. We find that the evolution of the mass-temperature relation is consistent with the self-similar evolution prediction, while the evolution of X-ray luminosity for a given temperature and mass for a given X-ray luminosity is slower than predicted by simple self-similar models. Our best fit results for the evolution factor E(z)^α are α =  −1.04    ±    0.07 for the M–T relation, $\mathit{\alpha }\mathrm{=}\mathrm{-}\mathrm{0.2}{\mathrm{3}}_{-0.62}^{\mathrm{+}\mathrm{0.12}}$ for the L–T relation, and $\mathit{\alpha }\mathrm{=}\mathrm{-}\mathrm{0.9}{\mathrm{3}}_{-0.12}^{\mathrm{+}\mathrm{0.62}}$ for the M–L_X relation. We also explore the influence of selection effects on scaling relations and find that selection biases are the most likely reason for apparent inconsistencies between different published data sets.

Conclusions. The new results provide the currently most robust calibration of high-redshift cluster mass estimates based on X-ray luminosity and temperature and help us to improve the prediction of the number of clusters to be found in future galaxy cluster X-ray surveys, such as eROSITA. The comparison of evolution results with hydrodynamical cosmological simulations suggests that early preheating of the intracluster medium (ICM) provides the most suitable scenario to explain the observed evolution.