The origin of the chemical elements in cluster cores

TL;DR

This paper reviews how X-ray observations reveal the origins, distribution, and evolution of metals in galaxy cluster cores, shedding light on star formation history and enrichment processes in the intracluster medium.

Contribution

It synthesizes current knowledge on chemical enrichment of the ICM using XMM-Newton data and discusses future prospects with upcoming X-ray observatories.

Findings

Elements originate mainly from supernovae and stellar processes.

Abundance patterns trace star formation history between redshifts 2-3.

Spatial and redshift evolution inform on metal transport mechanisms.

Abstract

Metals play a fundamental role in ICM cooling processes in cluster cores through the emission of spectral lines. But when and how were these metals formed and distributed through the ICM? The X-ray band has the unique property of containing emission lines from all elements from carbon to zinc within the 0.1-10 keV band. Using XMM-Newton, the abundances of about 11 elements are studied, which contain valuable information about their origin. Most elements were formed in type Ia and core-collapse supernovae, which have very different chemical yields. Massive stars and AGB stars also contribute by providing most of the carbon and nitrogen in the ICM. Because feedback processes suppress star formation in the cluster centre, the element abundances allow us to directly probe the star formation history of the majority of stars that are thought to have formed between z=2-3. The spatial distribution in the core and the evolution with redshift also provide information about how these elements are transported from the member galaxies to the ICM. I review the current progress in chemical enrichment studies of the ICM and give an outlook to the future opportunities provided by XMM-Newton's successors, like Astro-H.