Previous analyses of ASCA data of clusters of galaxies have found conflictingresults regarding the slope of the temperature profile of the hot X-ray gaswithin clusters, mainly because of the large, energy-dependent point spreadfunction (PSF) of the ASCA mirrors. We present a summary of all ASCA-determinedcluster temperature profiles found in the literature, and find a discrepancy inthe radial temperature trend of clusters based on which PSF-correction routineis used. This uncertainty in the cluster temperature profile in turn can leadto large uncertainties in the amount of dark matter in clusters. In this study,we have used ROSAT PSPC data to obtain independent relative temperatureprofiles for 26 clusters, most of which have had their temperature profilesdetermined by ASCA. Our aim is not to measure the actual temperature values ofthe clusters, but to use X-ray color profiles to search for a hardening orsoftening of the spectra with radius for comparison to ASCA-derived profiles.The radial color profiles indicate that outside of the cooling flow region, thetemperature profiles of clusters are in general constant. Within 35% of thevirial radius, we find a temperature drop of 20% at 10 keV and 12% at 5 keV canbe ruled out at the 99% confidence level. A subsample of non-cooling flowclusters shows that the condition of isothermality applies at very small radiitoo, although cooling gas complicates this determination in the cooling flowsubsample. The colors predicted from the temperature profiles of a series ofhydrodynamical cluster simulations match the data very well, although theycannot be used to discriminate among different cosmologies. An additionalresult is that the color profiles show evidence for a central peak inmetallicity in low temperature clusters.
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