The Cluster Population in a Complete Sample of Optically Identified RASS X-Ray Sources

Abstract.

Using the 2.1-m telescope of the Guillermo Haro Observatory (Cananea, Mexico) the optical counterparts of a count-rate and area limited complete subsample of the ROSAT All Sky Survey (RASS) have been identified. While the majority of the observed sources were found to be AGN or stars, 78 sources (12% of an identified objects) were found to be galaxy clusters with redshifts between 0.027 and 0.404. Most of these clusters had not been cataloged before. On the other hand, about 2/3 of the Abell clusters in our study areas were not detected as RASS sources. The X-ray bright clusters are on average more distant than the Abell clusters and tend to be dominated by central galaxies (corresponding to Bautz-Morgan types I and II).