Star Formation in High-Redshift Starburst Galaxies

TL;DR

This paper presents a model for star formation in high-redshift starburst galaxies, demonstrating that when accounting for variable CO-H2 conversion factors, these galaxies follow a universal star formation law with high gas fractions.

Contribution

It introduces a new model for the CO-H2 conversion factor that varies with galaxy properties, unifying star formation behavior across local and high-z galaxies.

Findings

Galaxies follow a unimodal Kennicutt-Schmidt law with index ~2.

Inferred gas fractions are 0.2-0.4, lower than previous estimates.

Variable CO-H2 conversion factors reconcile differences in gas fraction estimates.

Abstract

I present a model for the star formation properties of z~2 starburst galaxies. Here, I discuss models for the formation of high-z Submillimeter Galaxies, as well as the CO-H2 conversion factor for these systems. I then apply these models to literature observations. I show that when using a functional form for XCO that varies smoothly with the physical properties in galaxies, galaxies at both local and high-z lie on a unimodal Kennicutt-Schmidt star formation law, with power-law index of ~2. The inferred gas fractions of these galaxies are large (fgas ~ 0.2-0.4), though a factor ~2 lower than most literature estimates that utilize locally-calibrated CO-H2 conversion factors.