Iron in galaxy groups and clusters: Confronting galaxy evolution models with a newly homogenised dataset

TL;DR

This study compiles and homogenizes a large dataset of iron abundances in galaxy groups and clusters, compares it with galaxy evolution models, and discusses the physical processes influencing metal distribution.

Contribution

It provides the first comprehensive, homogenized low-redshift dataset of iron abundances in galaxy systems and evaluates galaxy evolution models against this dataset.

Findings

T-Z relation in clusters is tight with a slight negative gradient.

L-Galaxies overestimates Z in lower-temperature groups, indicating missing feedback processes.

Model matches observations for hot clusters from z ~ 1.3 to 0, but underestimates Z in intermediate-temperature clusters at z=0.

Abstract

We present an analysis of the iron abundance in the hot gas surrounding galaxy groups and clusters. To do this, we first compile and homogenise a large dataset 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 customised radial profiles for the temperature (T), gas density, and iron abundance (Z). We then compare this dataset to groups and clusters in the L-Galaxies galaxy evolution model. Our homogenised dataset reveals a tight T-Z relation for clusters, with a scatter in Z of only 0.10 dex and a slight negative gradient. After examining potential measurement biases, we conclude that at least some of this negative gradient has a physical origin. Our model suggests greater accretion of hydrogen in the hottest systems, via stripping of gas from infalling satellites, as a cause. At lower temperatures, L-Galaxies over-estimates Z in groups, indicating that metal-rich gas removal (via e.g. AGN feedback) is required. L-Galaxies provides a reasonable match to the observed Z in the intracluster medium (ICM) of the hottest clusters from at least z ~ 1.3 to 0.3. This is achieved without needing to modify any of the galactic chemical evolution (GCE) model parameters. However, the Z in intermediate-temperature clusters appears to be under-estimated in our model at z = 0. The merits and problems with modifying the GCE modelling to correct this are discussed.