Measurements of the gas contents of clusters of galaxies by observations of the background radiation at 10.6 GHz

Abstract

In a search for anisotropics in the microwave background radiation, we have observed 10 clusters of galaxies at 10.6 GHz for a total of 2275 hr. Significant depressions in the temperature of this radiation were found in the directions of two clusters, Abell 576 and 2218. The corresponding gas densities and temperatures at the cluster centres are about 10⁻²⁴ kg m⁻³ and 6 × 10⁸ K. Scans across A 576 provide a measure of the shape of the depression in the background. Our results are only partially consistent with those of Gull & Northover and Lake & Partridge.