Evolution of the metal content of the intra-cluster medium with hydrodynamical simulations

TL;DR

This study uses hydrodynamical simulations with different IMFs to analyze the evolution of metallicity in the intra-cluster medium, comparing results with X-ray observations and supernova rates.

Contribution

It introduces detailed chemical evolution modeling in galaxy cluster simulations with various IMFs and compares the evolution of ICM metallicity to observational data.

Findings

Simulations predict significant radial iron abundance gradients.

Metallicity evolution is driven by gas sinking, ongoing star formation, and metal locking in stars.

Stopping star formation at z=1 leads to faster metallicity evolution than observed.

Abstract

We present a comparison between simulation results and X-ray observational data on the evolution of the metallicity of the intra-cluster medium (ICM). The simulations of galaxy clusters were performed with the Tree-SPH Gadget2 code that includes a detailed model of chemical evolution, by assuming three different shapes for the stellar initial mass function (IMF), namely the Salpeter (1955), Kroupa (2001) and Arimoto-Yoshii (1987) IMF. Our simulations predict significant radial gradients of the Iron abundance, which extend over the whole cluster virialized region. At larger radii, we do not detect any flattening of the metallicity profiles. As for the evolution of the ICM metal (Iron) abundance out to z=1, we find that it is determined by the combined action of (i) the sinking of already enriched gas, (ii) the ongoing metal production in galaxies and (iii) the locking of ICM metals in newborn stars. As a result, rather than suppressing the metallicity evolution, stopping star formation at z=1 has the effect of producing an even too fast evolution of the emission-weighted ICM metallicity with too high values at low redshift. Finally, we compare simulations with the observed rate of type-Ia supernovae per unit B-band luminosity (SnU_B). We find that our simulated clusters do not reproduce the decreasing trend of SnU_B at low redshift, unless star formation is truncated at z=1.