Lights in the Dark: Globular clusters as dark matter tracers

TL;DR

This paper demonstrates that globular clusters serve as effective tracers for dark matter in galaxies, revealing insights into galaxy formation and dark matter accretion through empirical modeling and simulations.

Contribution

It extends an empirical model for globular cluster populations, showing their effectiveness in tracing dark matter and accretion history across galaxy types.

Findings

GC numbers correlate linearly with galaxy virial mass

GC abundances encode dark matter smooth accretion history

Model matches observational data across galaxy regimes

Abstract

A long-standing observed curiosity of globular clusters (GCs) has been that both the number and total mass of GCs in a galaxy are linearly correlated with the galaxy's virial mass, whereas its stellar component shows no such linear correlation. This work expands on an empirical model for the numbers and ages of GCs in galaxies presented by Valenzuela et al. (2021) that is consistent with recent observational data from massive elliptical galaxies down to the dwarf galaxy regime. Applying the model to simulations, GC numbers are shown to be excellent tracers for the dark matter (DM) virial mass, even when distinct formation mechanisms are employed for blue and red GCs. Furthermore, the amount of DM smooth accretion is encoded in the GC abundances, therefore providing a measure for an otherwise nearly untraceable component of the formation history of galaxies.