X-ray studies of clusters of galaxies with the Einstein Observatory

The paper reports on cluster observations made by the Columbia Astrophysics Laboratory with the Einstein Observatory. A plot of the 0.2-3.0 keV X-ray luminosity of two dozen randomly selected sources against the Bautz-Morgan class reveals no apparent correlation between X-ray brightness and cluster morphological type. Observing a field containing the Butcher and Oemler cluster CL0024+1654 (z = 0.39), the satellite detected a weak source coincident with the cluster center. An IPC (imaging proportional counter) image of the Coma cluster, the nearest and best studied of Abell's rich clusters, shows a smooth X-ray emission rising to a flat central plateau in the vicinity of the giant ellipticals, NGC4874 and NGC4889. Although individual galaxies emerge above the diffuse flux near the edge of the field at the level of 0.1% of the cluster emission, the central 40 minutes contain no fluctuations on the scale of approximately one minute to the 1%-level.