The formation and early evolution of embedded star clusters in spiral galaxies

TL;DR

This paper introduces Ekster, a novel simulation method combining SPH and N-body techniques to study star cluster formation within live galaxy models, enabling detailed analysis of early cluster evolution in different spiral arm environments.

Contribution

The paper presents Ekster, a new simulation approach that allows for high-resolution modeling of star and cluster formation in galaxy-scale environments.

Findings

Massive GMC regions produce more massive star clusters.

Cluster formation occurs via gas accretion and proto-cluster merging.

Stronger spiral arms lead to more frequent and massive cluster formation.

Abstract

We present Ekster, a new method for simulating star clusters from birth in a live galaxy simulation that combines the smoothed-particle hydrodynamics (SPH) method Phantom with the $N$-body method PeTar. With Ekster, it becomes possible to simulate individual stars in a simulation with only moderately high resolution for the gas, allowing us to study whole sections of a galaxy rather than be restricted to individual clouds. We use this method to simulate star and star cluster formation in spiral arms, investigating massive GMCs and spiral arm regions with lower mass clouds, from two galaxy models with different spiral potentials. After selecting these regions from pre-run galaxy simulations, we re-sample the particles to obtain a higher resolution. We then re-simulate these regions for 3 Myr to study where and how star clusters form. We analyse the early evolution of the embedded star clusters in these regions. We find that the massive GMC regions, which are more common with stronger spiral arms, form more massive clusters than the sections of spiral arms containing lower mass clouds. Clusters form both by accreting gas and by merging with other proto-clusters, the latter happening more frequently in the denser GMC regions.