Physical Properties and Scaling Relations of Molecular Clouds: the Impact of Star Formation

TL;DR

This study uses high-resolution hydrodynamical simulations to examine how different star formation criteria influence the properties and distribution of molecular clouds in a galaxy, revealing that the criteria affect cloud sizes and star formation sites but not fundamental cloud relations.

Contribution

It demonstrates that the choice of star formation criteria significantly impacts molecular cloud properties and star formation distribution, while leaving key cloud scaling relations unchanged.

Findings

Turbulent, self-gravitating criteria increase dense gas fractions.

Star formation sites differ with criteria, favoring high-density regions.

Cloud properties like Larson relations are unaffected by criteria.

Abstract

Using hydrodynamical simulations of a Milky Way-like galaxy, reaching 4.6 pc resolution, we study how the choice of star formation criteria impacts both galactic and Giant Molecular Clouds (GMC) scales. We find that using a turbulent, self-gravitating star formation criteria leads to an increase in the fraction of gas with densities between 10 and 10$^4$ cm$^{-3}$ when compared with a simulation using a molecular star formation method, despite both having nearly identical gaseous and stellar morphologies. Furthermore, we find that the site of star formation is effected with the the former tending to only produce stars in regions of very high density ($\gt 10$ cm$^{-3}$) gas while the latter forms stars along the entire length of its spiral arms. The properties of GMCs are impacted by the choice of star formation criteria with the former method producing larger clouds. Despite the differences we find that the relationships between clouds properties, such as the Larson relations, remain unaffected. Finally, the scatter in the measured star formation efficiency per free-fall time of GMCs remains present with both methods and is thus set by other factors.