The initial mass spectrum of old globular clusters in dwarf galaxies

TL;DR

This study compares the initial mass spectrum of old globular clusters in dwarf galaxies with young massive clusters in nearby galaxies, finding that most formed through similar processes, with some being nuclear clusters that grew via merging.

Contribution

It demonstrates that the initial mass spectrum of old GCs in dwarf galaxies aligns with that of YMCs, highlighting similar formation mechanisms and the potential nuclear origin of some GCs.

Findings

Most massive GCs are consistent with the same initial mass spectrum as YMCs.

Up to one third of Milky Way's metal-poor GCs may have a nuclear origin.

A log-normal ICMF is statistically inconsistent with observed GCs.

Abstract

We test whether the masses of old globular clusters (GCs) in dwarf galaxies are consistent with the same initial mass spectrum as young massive clusters (YMCs) in nearby star-forming galaxies. The most massive GCs of dwarf galaxies are compared to their expected masses when drawing from the Schechter-type ICMF of YMCs. It is found that the most massive GCs of galaxies in the stellar mass range M_*,gal=10^7-10^9 Msun are consistent with the same initial mass spectrum as YMCs in about 90% of the cases, suggesting that their formation mechanisms were the same. For the remaining 10%, the most massive clusters are nuclear GCs, which have been able to grow to higher masses through further merging after their initial formation ended. Because the effects of cluster disruption are weaker for more massive clusters, we estimate that up to one third of the metal-poor GCs in the Milky Way may have a nuclear origin, while the remaining two thirds formed through the same process as YMCs in the local universe. A log-normal ICMF is inconsistent with observed GCs at a 99.6% confidence level.