Dynamics of Star Cluster Formation: Mergers in Gas Rich Environments

TL;DR

This study uses high-resolution simulations to explore how mergers within gas-rich environments influence star cluster formation, revealing the role of gas in promoting mergers, inducing asymmetries, and affecting star formation and dynamics.

Contribution

It provides new insights into the impact of gas on cluster mergers and their dynamical signatures during star cluster formation.

Findings

GMC gas facilitates cluster mergers and growth.

Mergers induce asymmetry and angular momentum in clusters.

Background gas can increase dense gas and trigger new star formation.

Abstract

We perform high resolution simulations of forming star clusters as they merge inside giant molecular clouds (GMCs) using hydrodynamics coupled to N-body dynamics to simultaneously model both the gas and stars. We zoom in to previously run GMC simulations and resolve clusters into their stellar and gas components while including the surrounding GMC environment. We find that GMC gas is important in facilitating the growth of clusters in their embedded phase by promoting cluster mergers. Mergers induce asymmetric expansion of the stellar component of the clusters in our simulations. As well, mergers induce angular momentum in the clusters' stellar and gas components. We find that mergers can lead to an increase in the amount of dense gas present in clusters if a background gas distribution is present. We predict that this can lead to new star formation that can change the overall distribution of cluster stars in velocity space. Our results suggest that subcluster mergers in the presence of background gas can imprint dynamical signatures that can be used to constrain cluster formation histories.