Galactic Superbubbles in 3D: Wind Formation and Cloud Shielding

TL;DR

This paper uses hydrodynamical simulations to explore the formation of galactic winds driven by superbubbles and how cloud interactions influence the interstellar medium, advancing understanding of galaxy evolution.

Contribution

It presents a multi-scale simulation approach revealing how superbubble dynamics and cloud shielding affect galactic wind formation and interstellar medium regulation.

Findings

Supernova-driven superbubbles merge to form galactic winds.

Turbulence influences gas distribution and star formation.

Cloud shielding promotes cold gas retention during wind interactions.

Abstract

Galactic superbubbles are triggered by stellar feedback in the discs of star-forming galaxies. They are important in launching galactic winds, which play a key role in regulating the mass and energy exchange in galaxies. Observations can only reveal projected information and the 3D structure of such winds is quite complex. Therefore, numerical simulations are required to further our understanding of such structures. Here, we describe hydrodynamical simulations targeting two spatial scales. Large-scale superbubble models reveal supernova-driven outflows, and their subsequent merging, which leads to galactic wind formation. Additionally, the turbulence parameter $\sigma_t$ not only affects disc formation, but also influences mass and energy characteristics, controlling gas distribution and the injection rate in the simulated star formation zone. Small-scale wind-multicloud models indicate that isolated clouds are susceptible to instabilities, leading to fragmentation and dense gas destruction. In contrast, in closer cloud configurations, the condensation mechanism becomes important owing to hydrodynamic shielding, which helps to maintain the cold material throughout the evolution of the system. These simulations provide a comprehensive picture of galactic winds, showing how large-scale superbubble dynamics create the environment where small-scale wind-multicloud interactions shape the interstellar and circumgalactic media, ultimately regulating galaxy evolution.