The enrichment history of cosmic metals

TL;DR

This study uses cosmological simulations to trace the origin and enrichment history of cosmic metals, revealing how gas density, halo mass, and ejection timing influence metal distribution across different cosmic environments.

Contribution

It provides a detailed analysis of the timing, sources, and distribution of metals in the universe, highlighting the roles of galaxy mass and gas density in cosmic chemical enrichment.

Findings

Half of the metals in the diffuse IGM at z=0 were ejected from galaxies before redshift 2.

Lower density gas metals were typically ejected earlier by lower mass haloes.

Hotter IGM regions are enriched by a wider range of halo masses.

Abstract

We use a suite of cosmological, hydrodynamical simulations to investigate the chemical enrichment history of the Universe. Specifically, we trace the origin of the metals back in time to investigate when various gas phases were enriched and by what halo masses. We find that the age of the metals decreases strongly with the density of the gas in which they end up. At least half of the metals that reside in the diffuse intergalactic medium (IGM) at redshift zero (two) were ejected from galaxies above redshift two (three). The mass of the haloes that last contained the metals increases rapidly with the gas density. More than half of the mass in intergalactic metals was ejected by haloes with total masses less than 1e11 solar masses and stellar masses less than 1e9 solar masses. The range of halo masses that contributes to the enrichment is wider for the hotter part of the IGM. By combining the `when' and `by what' aspects of the enrichment history, we show that metals residing in lower density gas were typically ejected earlier and by lower mass haloes.