The correlation between the sizes of globular cluster systems and their host dark matter haloes

TL;DR

This study reveals a strong, non-linear correlation between the size of globular cluster systems and their host dark matter haloes, providing insights into galaxy formation and halo assembly history.

Contribution

It extends the known mass relation to system sizes, establishing a tight, non-linear relationship between GC system effective radius and halo virial radius.

Findings

GC system sizes follow a de Vaucouleurs profile.

Strong correlation between GC system size and halo virial radius.

Non-linear relationship suggests complex halo assembly processes.

Abstract

The sizes of entire systems of globular clusters (GCs) depend on the formation and destruction histories of the GCs themselves, but also on the assembly, merger and accretion history of the dark matter (DM) haloes that they inhabit. Recent work has shown a linear relation between total mass of globular clusters in the globular cluster system and the mass of its host dark matter halo, calibrated from weak lensing. Here we extend this to GC system sizes, by studying the radial density profiles of GCs around galaxies in nearby galaxy groups. We find that radial density profiles of the GC systems are well fit with a de Vaucouleurs profile. Combining our results with those from the literature, we find tight relationship ($\sim 0.2$ dex scatter) between the effective radius of the GC system and the virial radius (or mass) of its host DM halo. The steep non-linear dependence of this relationship ($R_{e, GCS} \propto R_{200}^{2.5 - 3}$) is currently not well understood, but is an important clue regarding the assembly history of DM haloes and of the GC systems that they host.