On the Internal Absorption of Galaxy Clusters

A study of the cores of galaxy clusters with the Einstein SSS indicated thepresence of absorbing material corresponding to 1E+12 Msun of cold cluster gas,possibly resulting from cooling flows. Since this amount of cold gas is notconfirmed by observations at other wavelengths, we examined whether this excessabsorption is present in the ROSAT PSPC observations of 20 bright galaxyclusters. For 3/4 of the clusters, successful spectral fits were obtained withabsorption due only to the Galaxy, and therefore no extra absorption is neededwithin the clusters, in disagreement with the results from the Einstein SSSdata for some of the same clusters. For 1/4 of the clusters, none of ourspectral fits was acceptable, suggesting a more complicated cluster medium thanthe two-temperature and cooling flow models considered here. However, even forthese clusters, substantial excess absorption is not indicated.Comment: accepted by the Astrophysical Journa