ROSAT PSPC Observations of the Richest ($R \geq 2$) ACO Clusters

TL;DR

This study presents a comprehensive X-ray analysis of 150 optically selected rich galaxy clusters from the ACO catalog using ROSAT PSPC data, exploring their properties, correlations, and catalog contamination.

Contribution

It provides the first systematic X-ray characterization of a large sample of optically selected rich clusters and assesses optical catalog contamination.

Findings

X-ray luminosity correlates with optical richness.

Quantitative estimate of contamination in the ACO catalog.

Derived X-ray luminosity function for different classifications.

Abstract

We have compiled an X-ray catalog of optically selected rich clusters of galaxies observed by the PSPC during the pointed GO phase of the ROSAT mission. This paper contains a systematic X-ray analysis of 150 clusters with an optical richness classification of $R \geq 2$ from the ACO catalog (Abell, Corwin, and Olowin 1989). All clusters were observed within 45' of the optical axis of the telescope during pointed PSPC observations. For each cluster, we calculate: the net 0.5-2.0 keV PSPC count rate (or $4 \sigma$ upper limit) in a 1 Mpc radius aperture, 0.5-2.0 keV flux and luminosity, bolometric luminosity, and X-ray centroid. The cluster sample is then used to examine correlations between the X-ray and optical properties of clusters, derive the X-ray luminosity function of clusters with different optical classifications, and obtain a quantitative estimate of contamination (i.e, the fraction of clusters with an optical richness significantly overestimated due to interloping galaxies) in the ACO catalog.