Iron in galaxy groups and clusters: confronting galaxy evolution models with a newly homogenized data set

We present an analysis of the iron abundance in the hot gas surrounding galaxy groups and clusters. To do this, we first compile and homogenize a large data set of 79 low-redshift (⁠|z = 0. 03|⁠) systems (159 individual measurements) from the literature. Our analysis accounts for differences in aperture size, solar abundance, and cosmology, and scales all measurements using customized radial profiles for the temperature (T), gas density (ρgas), and iron abundance (ZFe). We then compare this data set to groups and clusters in the L-Galaxies galaxy evolution model. Our homogenized data set reveals a tight T–ZFe relation for clusters, with a scatter in ZFe of only 0. 10 dex and a slight negative gradient. After examining potential measurement biases, we conclude that some of this negative gradient has a physical origin. Our model suggests greater accretion of hydrogen in the hottest systems, via stripping from infalling satellites, as a cause. In groups, L-Galaxies over-estimates ZFe, indicating that metal-rich gas removal (via e. g. AGN feedback) is required. L-Galaxies is consistent with the observed ZFe in the intracluster medium (ICM) of the hottest clusters at z = 0, and shows a similar rate of ICM enrichment as that observed from at least z ∼ 1. 3 to the present day. This is achieved without needing to modify any of the galactic chemical evolution (GCE) model parameters. However, the ZFe in intermediate-T clusters could be under-estimated in our model. We caution that modifications to the GCE modelling to correct this disrupt the agreement with observations of galaxies’ stellar components.