A Superbubble Feedback Model for Galaxy Simulations

TL;DR

This paper introduces a new stellar feedback model that accurately simulates superbubbles, improving the representation of gas motions and hot gas regulation in galaxy simulations, leading to more realistic star formation and outflows.

Contribution

The model incorporates thermal conduction, sub-grid evaporation, and a multi-phase treatment, enabling more realistic superbubble evolution in galaxy simulations.

Findings

Model reproduces superbubbles effectively.

Simulations show regulated star formation in galaxies.

Produces strong outflows consistent with observations.

Abstract

We present a new stellar feedback model that reproduces superbubbles. Superbubbles from clustered young stars evolve quite differently to individual supernovae and are substantially more efficient at generating gas motions. The essential new components of the model are thermal conduction, sub-grid evaporation and a sub-grid multi-phase treatment for cases where the simulation mass resolution is insufficient to model the early stages of the superbubble. The multi-phase stage is short compared to superbubble lifetimes. Thermal conduction physically regulates the hot gas mass without requiring a free parameter. Accurately following the hot component naturally avoids overcooling. Prior approaches tend to heat too much mass, leaving the hot ISM below $10^6$ K and susceptible to rapid cooling unless ad-hoc fixes were used. The hot phase also allows feedback energy to correctly accumulate from multiple, clustered sources, including stellar winds and supernovae. We employ high-resolution simulations of a single star cluster to show the model is insensitive to numerical resolution, unresolved ISM structure and suppression of conduction by magnetic fields. We also simulate a Milky Way analog and a dwarf galaxy. Both galaxies show regulated star formation and produce strong outflows.