ROSAT X-RAY OBSERVATIONS OF THE 2A-0335+096 CLUSTER OF GALAXIES

The 2A 0335+096 cluster of galaxies was observed in X-rays with the Po sition Sensitive Proportional Counter (PSPC) and the High Resolution I mager (HRI) on ROSAT. Spatially resolved X-ray spectra show a decrease in the ambient temperature of the X-ray emitting gas in the inner reg ions of the cluster, indicative of a cooling flow. The spectra also co nfirm the presence of an absorbing column density in excess of the mea sured Galactic value toward the cooling how region, which must be intr insic to the cluster. The mass of this absorbing matter is 7.4 x 10(11 ) M. within 170 kpc of the center of the cluster. A deprojection of th e surface brightness profile combined with the observed temperature pr ofile yields electron density, gas and gravitational mass, and mass de position rate profiles. Within 1.2 Mpc the total gravitating mass is 1 .9 x 10(14) M.. A cooling rate of 400(-65)(+90) M. yr(-1) is found wit hin the cooling radius of 166(-18)(+28) kpc. This value is consistent with the cooling rate obtained by fitting a cooling flow model to the spectrum of the central 166 kpc. Although the cooling rate is proporti onal to radius for the inner 60 kpc, it is essentially constant beyond this point, which suggests that the gas cools homogeneously in this r egion. A similar result was found for the NGC 5044 group of galaxies b y David et al. (1994). This disagrees with earlier observations of oth er clusters, which suggested that the gas within the entire cooling fl ow region was inhomogeneous.