The Structure of the X-Ray Emitting Gas in the Hydra-A Cluster of Galaxies

Abstract

The temperature and abundance structure in the intracluster medium (ICM) of the Hydra-A cluster of galaxies is studied with ASCA and ROSAT. The effect of the large extended outskirts in the point-spread function of the X-Ray Telescope on ASCA is included in this analysis. In the X-ray brightness profile, the strong central excess above a single beta-model, identified in the Einstein and ROSAT data, is also found in the harder energy band (>4keV). A simultaneous fit of five annular spectra taken with the GIS instrument shows a radial distribution of the temperature and metal abundance. A significant central enhancement in the abundance distribution is found, while the temperature profile suggests that the ICM is approximately isothermal with the temperature of ~3.5keV. The ROSAT PSPC spectrum in the central 1'.5 region indicates a significantly lower temperature than the GIS result. A joint analysis of the GIS and PSPC data reveals that the spectra can be described by a two temperature model as well as by a cooling flow model. In both cases, the hot phase gas with the temperature of ~3.5keV occupies more than 90% of the total emission measure within 1'.5 from the cluster center. The estimated mass of the cooler (0.5-0.7keV) component is ~2-6 x 10^9 M_solar, which is comparable to the mass of hot halos seen in non-cD ellipticals. The cooling flow model gives the mass deposition rate of 60+-30 M_solar/yr, an order of magnitude lower than the previous estimation.