Chemical enrichment in the cluster of galaxies Hydra A

Abstract

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 ∼120 ks 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) 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 1.6−6.1 × 10 9 M , and the energy associated with this uplift to 3.3−12.5 × 10 58 erg. The best estimate of the mass of Fe uplifted together with the cool gas is 1.7 × 10 7 M , 15% of the total mass of Fe in the central 0.5 region.

X-ray spectroscopy of galaxy clusters: studying astrophysical processes in the largest celestial laboratories

“…The relative abundances of the uplifted gas are consistent with those of the ambient ICM, indicating that the dominant fraction of metals in the cluster core was uplifted after the last major epoch of star formation and the relative enrichment rate by SN Ia with respect to that by stellar winds remains fairly constant with time. Uplift of metal rich cool gas from the cD galaxy by buoyantly rising bubbles of radio emitting plasma was also observed in the Hydra A cluster of galaxies (Simionescu et al 2009b). The total mass of the uplifted Fe in Hydra A is 1.7 × 10 7 M .…”

“…Recently, Simionescu et al (2009b) determined radial abundance profiles for O, Si, S, and Fe in the Hydra A cluster. They found that all elements have a centrally peaked distribution.…”

“…Can the abundance peaks be produced by only stellar winds and SN Ia in the cD galaxy? To explain the centrally peaked distribution of O, Si, and S in the Hydra A cluster would require the amount of metals produced by stellar winds to be 3-8 times higher than predicted by models or the metals produced by SN CC in the proto-cluster phase not to be mixed completely (Simionescu et al 2009b). Centrally peaked distribution of all elements can also be produced by ram-pressure stripping of cluster galaxies (e.g.…”

“…The brighter supernovae are expected to produce more Ni and less α elements (Si, S, Ar, Ca) than the fainter ones. Figure 36 shows the log 10 (Fe/Si) against the log 10 (Fe/O) for different spatial regions in clusters of galaxies Hydra A (Simionescu et al 2009b), Sérsic 159-03 (de Plaa et al 2006, Centaurus (Matsushita et al 2007a), Fornax (Matsushita et al 2007b), M 87 (Matsushita et al 2003), and A1060 (Sato et al 2007). The plot shows a relatively large spread in the abundance patterns determined for different clusters.…”

“…Using SN CC yields by different authors, assuming different progenitor pre-enrichment levels, or integrating the SN CC yields over a different IMF would move these curves (see Fig. 11 in Simionescu et al 2009b). But an intrinsic variation in the metallicity or IMF of the SN CC progenitors alone could not explain the observed variety of abundance patterns.…”