Constraining the origin and models of chemical enrichment in galaxy clusters using the Athena X-IFU

TL;DR

This paper demonstrates that the Athena X-IFU instrument will significantly improve our ability to understand the chemical enrichment history of galaxy clusters by accurately measuring metal abundances and constraining stellar initial mass functions across different redshifts.

Contribution

The study shows that the Athena X-IFU can recover input chemical enrichment models and constrain the stellar initial mass function with high precision using synthetic observations.

Findings

X-IFU can recover chemical enrichment models at various redshifts.

X-IFU can statistically exclude over 99.5% of alternative models.

Constraints on the stellar initial mass function slope within ~12%.

Abstract

The chemical enrichment of the Universe at all scales is related to stellar winds and explosive supernovae phenomena. Metals produced by stars and later spread at the mega-parsec scale through the intra-cluster medium (ICM) become a fossil record of the chemical enrichment of the Universe and of the dynamical and feedback mechanisms determining their circulation. As demonstrated by the results of the soft X-ray spectrometer onboard Hitomi, high resolution X-ray spectroscopy is the path to to differentiate among the models that consider different metal production mechanisms, predict the outcoming yields, and are function of the nature, mass, and/or initial metallicity of their stellar progenitor. Transformational results shall be achieved through improvements in the energy resolution and effective area of X-ray observatories to detect rare metals (e.g. Na, Al) and constrain yet uncertain abundances (e.g. C, Ne, Ca, Ni). The X-ray Integral Field Unit (X-IFU) instrument onboard the next-generation European X-ray observatory Athena is expected to deliver such breakthroughs. Starting from 100 ks of synthetic observations of 12 abundance ratios in the ICM of four simulated clusters, we demonstrate that the X-IFU will be capable of recovering the input chemical enrichment models at both low ($z = 0.1$) and high ($z = 1$) redshifts, while statistically excluding more than 99.5% of all the other tested combinations of models. By fixing the enrichment models which provide the best fit to the simulated data, we also show that the X-IFU will constrain the slope of the stellar initial mass function within $\sim$12%. These constraints will be key ingredients in our understanding of the chemical enrichment of the Universe and its evolution.