Modeling the High-z Universe: Probing Galaxy Formation

TL;DR

This paper explores how high-redshift conditions influence galaxy formation, emphasizing gas dynamics, star formation, and galaxy mergers, and presents models that align with observed galaxy size evolution and luminosity functions.

Contribution

It introduces a comprehensive model combining gas dissipation, cold accretion, and mergers to explain galaxy evolution at high redshift.

Findings

High-redshift gas accretion occurs on a halo dynamical time.

Cold accretion flows can drive turbulence if 20% of energy is converted.

The model reproduces observed size evolution of early-type galaxies.

Abstract

We discuss how the conditions at high redshift differ from those at low redshift, and what the impact is on the galaxy population. We focus in particular on the role of gaseous dissipation and its impact on sustaining high star formation rates as well as on driving star-bursts in mergers. Gas accretion onto galaxies at high redshifts occurs on a halo dynamical time allowing for very efficiently sustained star formation. In addition cold accretion flows are able to drive turbulence in high redshift disks at the level observed if at least 20% of the accretion energy is converted into random motion in the gaseous disk. In general we find that the fraction of gas involved in galaxy mergers is a strong function of time and increases with redshift. A model combining the role of dissipation during mergers and continued infall of satellite galaxies allows to reproduce the observed size-evolution of early-type galaxies with redshift. Furthermore we investigate how the evolution of the faint-end of the luminosity function can be explained in terms of the evolution of the underlying dark matter evolution.