Physical properties and scaling relations of molecular clouds: the impact of star formation

Abstract

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 cloud (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 $10^{4}{\, \rm {cm^{-3}}}$ 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 (${\gt}10^{4}{\, \rm {cm^{-3}}}$) 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.