How supernova explosions power galactic winds

TL;DR

This paper investigates how supernova explosions drive galactic winds using high-resolution simulations, revealing dependencies on disk properties and proposing a new physically motivated sub-grid model for galaxy formation simulations.

Contribution

It introduces a detailed numerical study of supernova-driven winds and develops a new sub-grid model based on physical insights for use in cosmological simulations.

Findings

Outflows are more efficient in disks with lower surface densities.

A simple model reproduces wind scaling with disk parameters.

Provides a new sub-grid wind model for galaxy formation simulations.

Abstract

Feedback from supernovae is an essential aspect of galaxy formation. In order to improve subgrid models of feedback we perform a series of numerical experiments to investigate how supernova explosions power galactic winds. We use the Flash hydrodynamic code to model a simplified ISM, including gravity, hydrodynamics, radiative cooling above 10,000 K, and star formation that reproduces the Kennicutt-Schmidt relation. By simulating a small patch of the ISM in a tall box perpendicular to the disk, we obtain sub-parsec resolution allowing us to resolve individual supernova events and we investigate how the wind properties depend on those of the ISM and the galaxy. We find that outflows are more efficient in disks with lower surface densities or gas fractions. A simple model in which the warm cloudy medium is the barrier that limits the expansion of blast waves reproduces the scaling of outflow properties with disk parameters at high star formation rates. The scaling we find sets the investigation of galaxy winds on a new footing, providing a physically motivated sub-grid description of winds that can be implemented in cosmological hydrodynamic simulations and phenomenological models. [Abridged]