Astronomy and Astrophysics, volume 493, 409-424 (2009/1-2)
Chemical enrichment in the cluster of galaxies Hydra A.
SIMIONESCU A., WERNER N., BOEHRINGER H., KAASTRA J.S., FINOGUENOV A., BRUEGGEN M. and NULSEN P.E.J.
Abstract (from CDS):
We analyzed global properties, radial profiles, and 2D maps of the metal abundances and temperature in the cool core cluster of galaxies Hydra A using a deep ∼120ks XMM-Newton exposure. The best fit among the available spectral models is provided by a Gaussian distribution of the emission measure (gdem). We can accurately determine abundances for 7 elements in the cluster core with EPIC (O, Si, S, Ar, Ca, Fe, Ni) and 3 elements (O, Ne, Fe) with RGS. The gdem model gives lower Fe abundances than a single-temperature model. Based on this, we explain why simulations show that the best-fit Fe abundance in clusters with intermediate temperatures is overestimated. The abundance profiles for Fe, Si, S, but also O are centrally peaked. Combining the Hydra A results with 5 other clusters for which detailed chemical abundance studies are available, we find a significant decrease in O with radius, while the increase in the O/Fe ratio with radius is small within 0.1r200, where the O abundances can be accurately determined, with d(O/Fe)/d(log10r/r200)=0.25±0.09. We compare the observed abundance ratios with the mixing of various supernova type Ia and core-collapse yield models in different relative amounts. Producing the estimated O, Si, and S peaks in Hydra A requires either the amount of metals ejected by stellar winds to be 3-8 times higher than predicted by available models or the initial enrichment by core-collapse supernovae in the protocluster phase not to be as well mixed on large scales as previously thought. The temperature map shows cooler gas extending in arm-like structures towards the north and south. These structures, and especially the northern one, appear to be richer in metals than the ambient medium and spatially correlated with the large-scale radio lobes. With different sets of assumptions, we estimate the mass of cool gas, which was probably uplifted by buoyant bubbles of relativistic plasma produced by the AGN, to 1.6-6.1x109M☉, and the energy associated with this uplift to 3.3-12.5x1058erg. The best estimate of the mass of Fe uplifted together with the cool gas is 1.7x107M☉, 15% of the total mass of Fe in the central 0.5' region.
X-rays: galaxies: clusters - galaxies: clusters: individual: Hydra A - galaxies: abundances - galaxies: cooling flows - galaxies: intergalactic medium
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