The link between star formation and gas in nearby galaxies

TL;DR

This study uses Bayesian modeling to analyze nearby galaxies, revealing that star formation is primarily governed by gas content and that variations in conversion efficiency are smaller than previously thought.

Contribution

It introduces a data-driven approach to understanding star formation regulation, emphasizing the role of gas content over efficiency variations in typical galaxies.

Findings

Star forming galaxies lie on a 'star forming plane' independent of stellar mass.

Star formation activity correlates strongly with molecular and total gas content.

Efficiency variations are smaller than previously reported, highlighting gas content as the main regulator.

Abstract

Observations of the interstellar medium are key to deciphering the physical processes regulating star formation in galaxies. However, observational uncertainties and detection limits can bias the interpretation unless carefully modeled. Here I re-analyze star formation rates and gas masses of a representative sample of nearby galaxies with the help of multi-dimensional Bayesian modeling. Typical star forming galaxies are found to lie in a 'star forming plane' largely independent of their stellar mass. Their star formation activity is tightly correlated with the molecular and total gas content, while variations of the molecular-gas-to-star conversion efficiency are shown to be significantly smaller than previously reported. These data-driven findings suggest that physical processes that modify the overall galactic gas content, such as gas accretion and outflows, regulate the star formation activity in typical nearby galaxies, while a change in efficiency triggered by, e.g., galaxy mergers or gas instabilities, may boost the activity of starbursts.