First Light And Reionisation Epoch Simulations (FLARES) VII: The Star Formation and Metal Enrichment Histories of Galaxies in the early Universe

TL;DR

This study uses FLARES simulations to explore galaxy star formation and metal enrichment histories at high redshifts, providing insights into their evolution and properties before JWST observations.

Contribution

It offers the first detailed predictions of galaxy star formation and chemical enrichment histories at z=5-13 using FLARES simulations, highlighting relationships with stellar mass and redshift.

Findings

Galaxy ages and specific star formation rates are mostly flat with stellar mass.

Galaxies show predominantly rising star formation histories that decrease with redshift and mass.

A strong stellar mass-metallicity relation and significant α-enhancement are predicted at high redshifts.

Abstract

The star formation and metal enrichment histories of galaxies - at any epoch - constitute one of the key properties of galaxies, and their measurement is a core aim of observational extragalactic astronomy. The lack of deep rest-frame optical coverage at high-redshift has made robust constraints elusive, but this is now changing thanks to the \emph{James Webb Space Telescope (JWST)}. In preparation for the constraints provided by \emph{JWST} we explore the star formation and metal enrichment histories of galaxies at $z=5-13$ using the First Light And Reionisation Epoch Simulations (FLARES) suite. Built on the EAGLE model, the unique strategy of FLARES allows us to simulate a wide range of stellar masses (and luminosities) and environments. While we predict significant redshift evolution of average ages and specific star formation rates our core result is a mostly flat relationship of age and specific star formation rate with stellar mass. We also find that galaxies in this epoch predominantly have strongly rising star formation histories, albeit with the magnitude dropping with redshift and stellar mass. In terms of chemical enrichment we predict a strong stellar mass - metallicity relation present at $z=10$ and beyond alongside significant $\alpha$-enhancement. Finally, we find no environmental dependence of the relationship between age, specific star formation rate, or metallicity with stellar mass.