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L.P. David (SAO), P.E.J. Nulsen (University of Wollongong), B.R. McNamara, W. Forman (SAO), B. Robertson (University of Washington)
The cooling flow cluster Hydra A was observed during the oribital activation and calibration phase of the Chandra observatory. While the X-ray image of the cluster exhibits complex structure in the central regions arising from an interaction between the radio lobes and hot gas, the large scale X-ray morphology of the cluster is farily smooth. A spectroscopic analysis of the ACIS data show that the gas temperature in Hydra A increases outward, reaches a maximum temperature of 4 keV at 200 kpc, and then decreases slightly at larger radii. The distribution of heavy elements is nonuniform, with a factor of two decrease in both the Fe and Si abundances within the central 100 kpc. One of the more surprising results is the lack of spectroscopic evidence for multiphase gas within the bulk of the cooling flow. Beyond the central 30 kpc, the ACIS spectra are adequately fit with a single temperature model. The addition of a cooling flow component does not significantly improve the fit. Only within the central 30 kpc (where the cooling time is less than 1 Gyr), is there spectroscopic evidence for multiphase gas. However, the spectroscopic mass deposition rate is a factor of 10 less the morphologically derived mass accretion rate at 30 kpc. In addition, we find that the total mass distribution within the central 200 kpc is characterized by a power-law distribution with an index of -1.3, intermediate between a NFW and Moore profile.