The properties of cooling flows in X-ray luminous clusters of galaxies

We discuss the X-ray properties of the cooling flows in a sample of thirtyhighly X-ray luminous clusters of galaxies observed with the ASCA and ROSATsatellites. We demonstrate the need for multiphase models to consistentlyexplain the spectral and imaging X-ray data for the clusters. The massdeposition rates of the cooling flows, independently determined from the ASCAspectra and ROSAT images, exhibit good agreement and exceed 1000 solar massesper year in the largest systems. We confirm the presence of intrinsic X-rayabsorption in the clusters using a variety of spectral models. The measuredequivalent hydrogen column densities of absorbing material are sensitive to thespectral models used in the analysis, varying from average values of a few10^{20} atom/cm^2 for a simple isothermal emission model, to a few 10^{21}atom/cm^2 using our preferred cooling flow models, assuming in each case thatthe absorber lies in a uniform foreground screen. The true intrinsic columndensities are likely to be even higher if the absorbing medium is distributedthroughout the clusters. We summarize the constraints on the nature of theX-ray absorber from observations in other wavebands. A significant part of theX-ray absorption may be due to dust.