Redshift evolution of the hot intracluster gas metallicity in the C-EAGLE cluster simulations

Abstract

The abundance and distribution of metals in galaxy clusters contains valuable information about their chemical history and evolution. By looking at how metallicity evolves with redshift, it is possible to constrain the different metal production channels. We use the C-EAGLE clusters, a sample of 30 high resolution (mgas ≃ 1.8 × 106 M⊙) cluster zoom simulations, to investigate the redshift evolution of metallicity, with particular focus on the cluster outskirts. The early enrichment model, in which the majority of metals are produced in the core of cluster progenitors at high redshift, suggests that metals in cluster outskirts have not significantly evolved since z = 2. With the C-EAGLE sample, we find reasonable agreement with the early enrichment model as there is very little scatter in the metallicity abundance at large radius across the whole sample, out to at least z = 2. The exception is Fe for which the radial dependence of metallicity was found to evolve at low redshift as a result of being mainly produced by Type Ia supernovae, which are more likely to be formed at later times than core-collapse supernovae. We also found considerable redshift evolution of metal abundances in the cores of the C-EAGLE clusters which has not been seen in other simulations or observation based metallicity studies. Since we find this evolution to be driven by accretion of low metallicity gas, it suggests that the interaction between outflowing, AGN heated material and the surrounding gas is important for determining the core abundances in clusters.

Chemical enrichment in groups and clusters

“…They reported an average metallicity in the 0.3 < r/R 500 < 1 radial range, about 0.21 ± 0.09 solar (in units of A09), which is consistent, albeit slightly lower than, the average outskirt metallicity of low-redshift clusters. Cosmological simulations provide similar results, also finding cluster metallicities that are consistent with no evolution at z 2, especially in the outskirts [7,90,67]. This is visible in Fig.…”