ChandraX‐Ray Spectroscopy and Imaging of the Galaxy Cluster PKS 0745−191

We present a detailed spectral and spatial analysis of the galaxy cluster PKS0745-191, using recent observations from the Chandra X-ray Observatory. Thedata provide information on the temperature and metallicity of the intraclustermedium, the distribution of emission throughout the cluster, morphology of thecluster core, and an independent mass estimate which can be compared to thatfrom gravitational lensing. X-ray spectra extracted from the central 300 kpc(~2 arcmin) are well described by a two-temperature plasma and the mean clustertemperature is consistent with previously determined values. The distributionof both temperature and metallicity within the inner 360 kpc (2.3 arcmin) ofPKS 0745-191 is probed on scales of 8 arcsec (~20 kpc), yielding a relativelyconstant abundance throughout the region and a strong temperature gradient(down to ~4-5 keV) within the central 215 kpc. Beta-model fits to the surfacebrightness profile of PKS 0745-191 indicate that a second beta-model componentis required to fit the inner ~10 kpc. Imaging analysis of the cluster corereveals an irregular morphology within the inner 50 kpc, and confirms that theX-ray emission peak lies within 0.5 arcsec (the spatial resolution of Chandra)of both the optical and radio central cD positions. The cluster mass, based onboth two temperature and multiphase fits to the X-ray spectrum, is in closeagreement with lensing mass estimates of PKS-0745-191.Comment: 30 pages, 4 tables, 10 figure