Feedback and the Structure of Simulated Galaxies at redshift z=2

TL;DR

This study uses cosmological simulations to analyze how different feedback mechanisms influence the properties and structures of high-redshift galaxies at z=2, revealing the impact on galaxy mass, morphology, and disk formation.

Contribution

It compares various feedback models in simulations to understand their effects on galaxy properties and morphology at high redshift.

Findings

Feedback significantly alters galaxy baryonic mass.

Galaxy disks are common in moderate-feedback scenarios.

Simulated galaxy properties align with observed high-redshift galaxy diversity.

Abstract

We study the properties of simulated high-redshift galaxies using cosmological N-body/gasdynamical runs from the OverWhelmingly Large Simulations (OWLS) project. The runs contrast several feedback implementations of varying effectiveness: from no-feedback, to supernova-driven winds to powerful AGN-driven outflows. These different feedback models result in large variations in the abundance and structural properties of bright galaxies at z=2. We find that feedback affects the baryonic mass of a galaxy much more severely than its spin, which is on average roughly half that of its surrounding dark matter halo in our runs. Feedback induces strong correlations between angular momentum content and galaxy mass that leave their imprint on galaxy scaling relations and morphologies. Encouragingly, we find that galaxy disks are common in moderate-feedback runs, making up typically ~50% of all galaxies at the centers of haloes with virial mass exceeding 1e11 M_sun. The size, stellar masses, and circular speeds of simulated galaxies formed in such runs have properties that straddle those of large star-forming disks and of compact early-type galaxies at z=2. Once the detailed abundance and structural properties of these rare objects are well established it may be possible to use them to gauge the overall efficacy of feedback in the formation of high redshift galaxies.