Disk Turbulence and Star Formation Regulation in High$-z$ Main Sequence Analogue Galaxies

TL;DR

This study uses high-resolution ALMA and HST observations of local galaxy analogues to high-redshift main sequence galaxies, revealing high turbulence levels and gas properties that support feedback-regulated star formation models over gravitational energy dissipation theories.

Contribution

It provides detailed kpc-scale measurements of molecular gas turbulence and star formation in local analogues, testing and constraining star formation theories at high redshift.

Findings

DYNAMO galaxies are more gas-rich than local star-forming galaxies.

Observed velocity dispersions align with feedback-regulated models.

Models combining gravitational energy dissipation overestimate turbulence.

Abstract

The gas-phase velocity dispersions in disk galaxies, which trace turbulence in the interstellar medium, are observed to increase with lookback time. However, the mechanisms that set this rise in turbulence are observationally poorly constrained. To address this, we combine kiloparsec-scale ALMA observations of CO(3-2) and CO(4-3) with HST observations of H$\alpha$ to characterize the molecular gas and star formation properties of seven local analogues of main sequence galaxies at $z \sim 1-2$, drawn from the DYNAMO sample. Investigating the ''molecular gas main sequence'' on kpc-scales, we find that galaxies in our sample are more gas-rich than local star-forming galaxies at all disk positions. We measure beam smearing corrected molecular gas velocity dispersions and relate them to the molecular gas and star formation rate surface densities. Despite being relatively nearby ($z \sim 0.1$), DYNAMO galaxies exhibit high velocity dispersions and gas and star formation rate surface densities throughout their disks, when compared to local star forming samples. Comparing these measurements to predictions from star formation theory, we find very good agreements with the latest feedback-regulated star formation models. However, we find that theories which combine gravitational energy dissipation from radial gas transport with feedback over-estimate the observed molecular gas velocity dispersions.