The role of galaxy mergers on the evolution of star clusters

TL;DR

This study uses detailed simulations to examine how galaxy mergers influence star cluster evolution, finding that long-term effects are mainly orbital, while short-term tidal effects are minimal for dense clusters.

Contribution

It introduces a novel simulation approach combining galactic tidal fields with star-by-star cluster models to study merger impacts.

Findings

Clusters in merger remnants lose mass faster.

Ejected clusters survive longer in tidal debris.

Short-lived tidal perturbations have limited impact on dense clusters.

Abstract

Interacting galaxies favor the formation of star clusters but are also suspected to affect their evolution through an intense and rapidly varying tidal field. Treating this complex behaviour remains out-of-reach of (semi-)analytical studies. By computing the tidal field from galactic models and including it into star-by-star N-body simulations of star clusters, we monitor the structure and mass evolution of a population of clusters in a galaxy major merger, taking the Antennae galaxies (NGC 4038/39) as a prototype. On the long timescale (~ 10^9 yr), the merger only indirectly affects the evolution of clusters by modifying their orbits in or around the galaxies: the mass-loss of clusters in the merger remnant is faster, while clusters ejected in the tidal debris survive much longer, compared to in an isolated galaxy. The tidal perturbations of the galactic collisions themselves are too short lived and not strong enough to significantly influence the structure and dissolution of realistically dense/massive star clusters.