High-resolution simulations of galaxy mergers: Resolving globular cluster formation

TL;DR

This study uses the highest resolution galaxy merger simulation to demonstrate that massive star clusters formed during mergers are likely progenitors of globular clusters, with properties matching observations.

Contribution

The paper presents the first high-resolution simulation resolving the formation of massive star clusters in galaxy mergers, supporting their role as globular cluster progenitors.

Findings

Massive star clusters of 10^5 to 10^7 solar masses are formed during galaxy mergers.

Formed clusters are tightly bound, with little net rotation, and evolve into long-lived stellar systems.

The cluster mass spectrum aligns with theoretical predictions and observational data.

Abstract

Massive star clusters observed in galaxy mergers are often suggested to be progenitors of globular clusters. To study this hypothesis, we performed the highest resolution simulation of a gas-rich galaxy merger so far. The formation of massive star clusters of 10^5 to 10^7 Mo, triggered by the galaxy interaction, is directly resolved in this model. We show that these clusters are tightly bound structures with little net rotation, due to evolve into compact long-lived stellar systems. Massive clusters formed in galaxy mergers are thus robust candidates for progenitors of long-lived globular clusters. The simulated cluster mass spectrum is consistent with theory and observations. Tidal dwarf galaxies of 10^8-9 Mo can form at the same time, and appear to be part of a different class of objects, being more extended and rotating.