Redshift Evolution in the Iron Abundance of the Intracluster Medium

TL;DR

This study investigates the evolution of iron abundance in the intracluster medium of galaxy clusters over cosmic time, revealing a significant decrease in metallicity from redshift 0 to 1.

Contribution

It provides the first comprehensive analysis combining multiple datasets to demonstrate metallicity evolution in galaxy clusters across a wide redshift range.

Findings

Metallicity decreases by about a factor of two from z=0 to z=1.

No significant evolution detected in the initial dataset alone.

Best-fit linear relation for metallicity evolution is Z(z)/Z_sun = 0.46 - 0.38z.

Abstract

Clusters of galaxies provide a closed box within which one can determine the chemical evolution of the gaseous baryons with cosmic time. We studied this metallicity evolution in the hot X-ray emitting baryons through an analysis of XMM-Newton observations of 29 galaxy clusters in the redshift range 0.3 < z < 1.3. Taken alone, this data set does not show evidence for significant evolution. However, when we also include a comparable sample of 115 clusters observed with Chandra (Maughan et al. 2008) and a lower redshift sample of 70 clusters observed with XMM at z < 0.3 (Snowden et al. 2008), there is definitive evidence for a decrease in the metallicity. This decrease is approximately a factor of two from z = 0 to z \approx 1, over which we find a least-squares best-fit line Z(z) / Z_{\odot} = (0.46 \pm 0.05) - (0.38 \pm 0.03)z. The greatest uncertainty in the evolution comes from poorly constrained metallicities in the highest redshift bin.