Evolution of galaxy stellar masses and star formation rates in the EAGLE simulations

TL;DR

The EAGLE simulations successfully model the evolution of galaxy stellar masses and star formation rates, closely matching observed data across a wide range of redshifts and providing insights into galaxy formation physics.

Contribution

This study demonstrates that the EAGLE hydrodynamical simulations accurately reproduce observed galaxy mass growth and star formation rate evolution, validating their physical models.

Findings

Simulations reproduce the observed growth of stellar mass density within 20%.

Galaxy stellar mass function evolution matches observations up to redshift z=7.

Simulated specific star formation rates are bimodal and evolve similarly to observed rates.

Abstract

We investigate the evolution of galaxy masses and star formation rates in the Evolution and Assembly of Galaxies and their Environment (EAGLE) simulations. These comprise a suite of hydrodynamical simulations in a $\Lambda$CDM cosmogony with subgrid models for radiative cooling, star formation, stellar mass loss, and feedback from stars and accreting black holes. The subgrid feedback was calibrated to reproduce the observed present-day galaxy stellar mass function and galaxy sizes. Here we demonstrate that the simulations reproduce the observed growth of the stellar mass density to within 20 per cent. The simulation also tracks the observed evolution of the galaxy stellar mass function out to redshift z = 7, with differences comparable to the plausible uncertainties in the interpretation of the data. Just as with observed galaxies, the specific star formation rates of simulated galaxies are bimodal, with distinct star forming and passive sequences. The specific star formation rates of star forming galaxies are typically 0.2 to 0.4 dex lower than observed, but the evolution of the rates track the observations closely. The unprecedented level of agreement between simulation and data makes EAGLE a powerful resource to understand the physical processes that govern galaxy formation.