HEAO 1 hard X-ray observations of three Abell clusters of galaxies

Abstract

The authors present the results of hard X-ray measurements of A1367, Coma (A1656), and A2319 clusters of galaxies made with the Low Energy Detectors on HEAO 1. Nonthermal components were not detected above the level of 10<SUP>-5</SUP> photons cm<SUP>-2</SUP>s<SUP>-1</SUP>keV<SUP>-1</SUP>, but the energy extensions of the thermal spectra of Coma and A2319 seen at lower energies were observed. These results are used to set lower limits on the mean magnetic field and upper limits on the energy density of relativistic electrons in the intracluster space of these clusters.