# Implementing Dust Shielding as a Criteria for Star Formation

## TL;DR

This paper introduces a dust shielding-based star formation model for galaxy simulations, showing it produces similar galaxy properties to H2-based models and aligns with observed star formation laws.

## Contribution

The paper presents a novel sub-grid model linking star formation to dust shielding, tested against other criteria in galaxy simulations.

## Key findings

- Shielding model allows star formation at higher temperatures and lower densities.
- Both shielding and H2-based models produce similar galaxy properties.
- Models reproduce the observed Kennicutt-Schmidt law.

## 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 sub-grid 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 sub-solar 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 H$_2$ fraction as star formation criteria. We further followed the evolution of a dwarf galaxy within a cosmological context using both the shielding and H$_2$-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 H$_2$ abundance, as requiring H$_2$ formation leads the gas to undergo additional gravitational collapse before star formation. However, the resulting galaxies are very similar for both the shielding and H$_2$-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.