Quasi-equilibrium models of high-redshift disc galaxy evolution

TL;DR

This paper introduces physically motivated galaxy evolution models for high-redshift galaxies, demonstrating that feedback physics largely governs stellar mass relations and star formation rates, providing insights into early galaxy formation.

Contribution

The paper presents a new set of galaxy models that incorporate sophisticated feedback and star formation physics, extending simple phenomenological models to better understand high-redshift galaxy evolution.

Findings

Stellar mass--halo mass relation depends mainly on feedback physics.

Specific star formation rate is proportional to cosmological accretion rate.

Gas mass is sensitive to star formation physics and feedback effects.

Abstract

In recent years, simple models of galaxy formation have been shown to provide reasonably good matches to available data on high-redshift luminosity functions. However, these prescriptions are primarily phenomenological, with only crude connections to the physics of galaxy evolution. Here we introduce a set of galaxy models that are based on a simple physical framework but incorporate more sophisticated models of feedback, star formation, and other processes. We apply these models to the high-redshift regime, showing that most of the generic predictions of the simplest models remain valid. In particular, the stellar mass--halo mass relation depends almost entirely on the physics of feedback (and is thus independent of the details of small-scale star formation) and the specific star formation rate is a simple multiple of the cosmological accretion rate. We also show that, in contrast, the galaxy's gas mass is sensitive to the physics of star formation, although the inclusion of feedback-driven star formation laws significantly changes the naive expectations. While these models are far from detailed enough to describe every aspect of galaxy formation, they inform our understanding of galaxy formation by illustrating several generic aspects of that process, and they provide a physically-grounded basis for extrapolating predictions to faint galaxies and high redshifts currently out of reach of observations. If observations show violations from these simple trends, they would indicate new physics occurring inside the earliest generations of galaxies.