Large-eddy simulations of isolated disc galaxies with thermal and turbulent feedback

TL;DR

This paper introduces a new subgrid-scale model called MIST for simulating the multi-phase interstellar medium, star formation, and turbulence in isolated disc galaxies using large-eddy simulations, capturing key physical processes.

Contribution

The paper presents the MIST model, which accounts for unresolved turbulence and phase interactions, improving galaxy simulation realism and reproducing observed star formation properties.

Findings

Reproduces observed star formation efficiency (~1%)

Matches typical velocity dispersions (~10 km/s) in star-forming regions

Shows a linear relation between star formation and dense molecular gas column densities

Abstract

We present a subgrid-scale model for the Multi-phase Interstellar medium, Star formation, and Turbulence (MIST) and explore its behaviour in high-resolution large-eddy simulations of isolated disc galaxies. MIST follows the evolution of a clumpy cold and a diffuse warm component of the gas within a volume element which exchange mass and energy via various cooling, heating and mixing processes. The star formation rate is dynamically computed from the state of the gas in the cold phase. An important feature of MIST is the treatment of unresolved turbulence in the two phases and its interaction with star formation and feedback by supernovae. This makes MIST a particularly suitable model for the interstellar medium in galaxy simulations. We carried out a suite of simulations varying fundamental parameters of our feedback implementation. Several observational properties of galactic star formation are reproduced in our simulations, such as an average star formation efficiency ~1%, a typical velocity dispersion around ~10 km/s in star-forming regions, and an almost linear relationship between the column densities of star formation and dense molecular gas.