A critical assessment of the metal content of the ICM

TL;DR

This paper assesses the metal content of the intracluster medium in massive galaxy clusters using existing abundance profiles, highlighting uncertainties and the need for future observations to better constrain metal distribution, especially in outskirts.

Contribution

It provides a comprehensive estimate of ICM metal abundance in nearby clusters and discusses the challenges and future prospects for measuring metals in cluster outskirts.

Findings

ICM metal abundance within r_180 is poorly constrained (0.06Z_sol to 0.26Z_sol).

Current measurements show no tension with theoretical expectations.

Future X-ray observatories could improve abundance estimates in cluster outskirts.

Abstract

Our goal is to provide a robust estimate of the metal content of the ICM in massive clusters. We make use of published abundance profiles for a sample of ~60 nearby systems, we include in our estimate uncertainties associated to the measurement process and to the almost total lack of measures in cluster outskirts. We perform a first, albeit rough, census of metals finding that the mean abundance of the ICM within r_180 is very poorly constrained, 0.06Z_sol < Z < 0.26Z_sol, and presents no tension with expectations. Similarly, the question of if and how the bulk of the metal content in clusters varies with cosmic time, is very much an open one. A solid estimate of abundances in cluster outskirts could be achieved by combining observations of the two experiments which will operate on board Athena, the XIFU and the WFI, provided they do not fall victim to the de-scoping process that has afflicted several space observatories over the last decade.