A model for molecular hydrogen-dependent star formation in simulations of galaxy evolution

TL;DR

This paper introduces a new star formation model in galaxy simulations that accounts for molecular hydrogen formation and chemical abundance, improving the understanding of star formation processes in Milky Way-like galaxies.

Contribution

A novel star formation model incorporating molecular hydrogen formation and chemical dependencies, applied to high-resolution galaxy simulations.

Findings

The model reproduces observed star formation rates in Milky Way-mass galaxies.

It highlights the importance of molecular gas in star formation.

Comparison with observations validates the model's effectiveness.

Abstract

Star formation, together with the associated chemical and energy feedback, is one of the most important processes in galaxy evolution. The star formation activity in galaxies defines and affects many of their fundamental properties, such as stellar mass, morphology and chemical enrichment levels. Simple models for star formation in cosmological hydrodynamical simulations have shown to be successful in reproducing the star formation rate (SFR) levels and shapes of different types of galaxies. However, with the advent of high-resolution simulations and more detailed observations, more sophisticated star formation models are needed; in particular, to better understand the relation between star formation and the amount of gas in the atomic and molecular phases. In this work, we apply a novel star formation model, recently developed to work in the context of hydrodynamical simulations, to the study of the SFR in Milky Way-mass galaxies. The new implementation describes the formation of molecular hydrogen from atomic material, considering also possible dependencies with the chemical abundance of the gas. This allows to implement various star formation models, where the SFR of a gas cloud is determined by the atomic and/or molecular gas phases, and to compare their predictions to recent observational results.