The Metal Abundance of High-Redshift Galaxy Clusters with Suzaku
Abstract
The metal enrichment history of the intra-cluster medium (ICM) encodes the history of star formation, the evolution of cluster galaxies, and the interactions between those galaxies and the intergalactic medium. Measuring cluster metal abundance as a function of redshift can constrain models of these processes, however until recently such measurements have been complicated by a lack of detected high-redshift clusters and by the low X-ray flux of such distant clusters. The advent of surveys exploiting the Sunyaev-Zel’dovich (SZ) effect has begun to greatly expand the number of high-redshift clusters available for study. One such project, the South Pole Telescope (SPT) cluster survey, has resulted in a uniquely high median redshift (<z> = 0.74) among cluster samples, and this presents an opportunity to trace the evolution of ICM metal enrichment to high redshift.
We here present Suzaku X-ray Observatory observations of four clusters at z = 0.7-1.1 which have been identified by the SPT cluster survey. These high-quality data allow among the most precise measurements of the ICM metal abundance to date at these redshifts: we find Fe abundances in the range 0.26-0.45 solar, with 1-σ uncertainties of 25-30%. These enhanced metal abundances are in tension with simulations that predict a decrease in Fe abundance of 50% from the local universe to z 1, and compared to previous results they point to a significant variation in cluster metallicity at early times. We discuss the possible implications of these results on metal enrichment models and future prospects for greatly expanding the sample of high-redshift clusters with high-quality metal abundance measurements.- Publication:
-
American Astronomical Society Meeting Abstracts #220
- Pub Date:
- May 2012
- Bibcode:
- 2012AAS...22043504M