2018MNRAS.477.3869H

The sizes of entire systems of globular clusters (GCs) depend not only 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 GCs in the GC system and the mass of its host DM 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 (∼0.2 dex scatter) between the effective radius of the GC system and the virial radius (or mass) of its host DM halo, for haloes with masses greater than ∼10¹² M_☉. The steep non-linear dependence of this relationship (R_ e, GCS_ ∝R₂₀₀^2.5 - 3^ ∝M₂₀₀^0.8 - 1^) 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.