X-Ray Emission Line Ratios and Multiphase Gas in Elliptical Galaxies and Galaxy Clusters
Abstract
We examine isothermal and simple multiphase models of the hot gas in elliptical galaxies and galaxy clusters to determine the most effective X-ray emission line ratios for constraining the emission measure distribution as a function of temperature in these systems. To facilitate quantitative comparison between different multiphase models we introduce the dimensionless multiphase strength, sigma_xi, which essentially measures the width of the emission measure distribution. Comparison of line ratios of two temperature and cooling flow models is presented in detail. Using K shell line ratios we find evidence for multiphase gas in NGC 4636, M87, and the Centaurus cluster, although the best available ASCA data do not provide useful constraints for most ellipticals. Prospects for determining the temperature structure in these systems are examined for the upcoming missions AXAF and ASTRO-E. Finally, we comment on recent evidence for resonance scattering in clusters.Keywords
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