A Complete Sample of 12 Very X-Ray Luminous Galaxy Clusters at z > 0.5

Abstract

We present the statistically complete and cosmologically most relevant subset of the 12 most distant galaxy clusters detected at by the Massive Cluster Survey (MACS). Ten of these systems are new discoveries; z 1 0.5 only two (MACS J0018.5ϩ1626, aka Cl 0016ϩ1609, and MACS J0454.1Ϫ0300, aka MS 0451.6Ϫ0305) were previously known. We provide fundamental cluster properties derived from our optical and X-ray follow-up observations as well as the selection function in tabulated form to facilitate cosmological studies using this sample.