A Cluster Deficit in the ROSAT NEP Survey
نویسنده
چکیده
We have used data from the deepest region of the ROSAT All−Sky Survey, the North Ecliptic Pole (NEP) region, to produce a complete and unbiased X−ray selected sample of distant clusters to understand the nature of cluster evolution and determine implications for large scale structure models. In this contribution results are presented from a comparison between the number of the observed clusters in the NEP survey and the number of expected clusters assuming no−evolution models. There is a deficit by a factor of 2.5−4 of high luminosity, high redshift clusters with respect to the present. The evolution goes in the same direction as the original EMSS result, and the results from the CfA−IfA 160 deg survey by [17].
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