Tracing the distribution and evolution of Iron in the IntraCluster Medium

TL;DR

This paper studies the distribution and evolution of Iron in the intra-cluster medium of galaxy clusters using X-ray data, revealing early enrichment and ongoing processes affecting chemical composition over cosmic time.

Contribution

It provides new measurements of Iron abundance evolution up to redshift 1.3, confirming early enrichment and proposing a model involving star formation and galaxy morphological transitions.

Findings

Iron abundance increases by a factor of ~2 from z=1.3 to present

ICM is already enriched at a look-back time of 9 Gyr

Enrichment pattern consistent with prompt star formation and galaxy evolution processes

Abstract

Emission lines in X-ray spectra of clusters of galaxies reveal the presence of heavy elements in the diffuse hot plasma (ICM) in virial equilibrium in the dark matter potential well. Thanks to the X-ray satellites Chandra and XMM-Newton we are now able to measure with good accuracy the distribution and evolution of Iron up to redshift z ~ 1.3. The capability of studying the chemical and thermodynamical properties of the ICM in high redshift clusters is an efficient tool to constrain the interaction processes between the cluster galaxies and the surrounding medium. We confirm that the ICM is already significantly enriched at a look-back time of 9 Gyr, and find that the Iron abundance change with redshift as (1+z)^(-1.25), implying an increase of a factor of ~2 with respect to z=1.3. This result can be explained by a prompt enrichment by star formation processes in massive ellipticals at z>2, followed by a slower release of enriched gas from disk galaxies into the ICM, associated to a morphological transition from disk to S0.