The Impact of Galactic Disc Environment on Star-Forming Clouds

TL;DR

This study investigates how different galactic disc environments, including rotation curves and spiral potentials, influence the formation and properties of star-forming clouds in galaxy simulations.

Contribution

It demonstrates that galactic rotation curves minimally affect cloud properties, but spiral perturbations significantly alter cloud structure and distribution.

Findings

Cloud properties are largely unaffected by rotation curve variations.

Spiral potential induces larger, extended, and unbound cloud structures.

Environment influences initial cloud formation locations, not average properties.

Abstract

We explore the effect of different galactic disc environments on the properties of star-forming clouds through variations in the background potential in a set of isolated galaxy simulations. Rising, falling and flat rotation curves expected in halo dominated, disc dominated and Milky Way-like galaxies were considered, with and without an additional two-arm spiral potential. The evolution of each disc displayed notable variations that are attributed to different regimes of stability, determined by shear and gravitational collapse. The properties of a typical cloud were largely unaffected by the changes in rotation curve, but the production of small and large cloud associations was strongly dependent on this environment. This suggests that while differing rotation curves can influence where clouds are initially formed, the average bulk properties are effectively independent of the global environment. The addition of a spiral perturbation made the greatest difference to cloud properties, successfully sweeping the gas into larger, seemingly unbound, extended structures and creating large arm-interarm contrasts.