Abstract
Star formation is observed to be strongly correlated to dense regions of molecular gas. Although the exact nature of the link between star formation and molecular hydrogen is still unclear, some have suggested that shielding of dense gas by dust grains is the key factor enabling the presence of both. We present a subgrid model for use in galaxy formation simulations in which star formation is linked explicitly to local dust shielding. We developed and tested our shielding and star formation models using smoothed particle hydrodynamic simulations of solar and subsolar metallicity isolated Milky Way-mass disk galaxies. We compared our dust-shielding-based star formation model to two other star formation recipes that used gas temperature and H2 fraction as star formation criteria. We further followed the evolution of a dwarf galaxy within a cosmological context using both the shielding and H2-based star formation models. We find that the shielding-based model allows for star formation at higher temperatures and lower densities than a model in which star formation is tied directly to H2 abundance, as requiring H2 formation leads the gas to undergo additional gravitational collapse before star formation. However, the resulting galaxies are very similar for both the shielding and H2-based star formation models, and both models reproduce the resolved Kennicutt-Schmidt law. Therefore, both star formation models appear viable in the context of galaxy formation simulations.