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Cluster Evolution in the ROSAT North Ecliptic Pole Survey

I. M. Gioia·J. P. Henry·C. R. Mullis·W. Voges·U. G. Briel·H. Boehringer·J. P. Huchra
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Abstract

The deepest region of the ROSAT All-Sky Survey, at the North Ecliptic Pole, has been studied to produce a complete and unbiased X-ray selected sample of clusters of galaxies. This sample is used to investigate the nature of cluster evolution and explore potential implications for large-scale structure models. The survey is 99.6% optically identified. Spectroscopic redshifts have been measured for all the extragalactic identifications. In this Letter, first results on cluster evolution are presented based on a comparison between the number of the observed clusters in the North Ecliptic Pole survey and the number of expected clusters assuming no-evolution models. At z>0.3 there is a deficit of clusters with respect to the local universe which is significant at > 4.7sigma. The evolution appears to commence at L_{0.5-2.0} > 1.8x10^{44} erg s^{-1} in our data. The negative evolution goes in the same direction as the original EMSS result, the results from the 160 deg^{2} survey by Vikhlinin et al. (1998) and the recent results from the RDCS (Rosati et al. 2000). At lower redshifts there is no evidence for evolution, a result in agreement with these and other cluster surveys.

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I. M. Gioia, J. P. Henry, C. R. Mullis, W. Voges, U. G. Briel, H. Boehringer, J. P. Huchra. 2001-04-18. Cluster Evolution in the ROSAT North Ecliptic Pole Survey. https://doi.org/10.1086/320671

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