Dark Matter Halos in Galaxies and Globular Cluster Populations

Understand

We combine a new, comprehensive database for globular cluster populations in all types of galaxies with a new calibration of galaxy halo masses based entirely on weak lensing.

• Correlating these two sets of data, we find that the mass ratio $\eta \equiv M_{GCS}/M_{h}$ (total mass in globular clusters, divided by halo mass) is essentially constant at $\langle \eta \rangle \sim 4 \times 10^{-5}$, strongly confirming earlier suggestions in the literature.
• Globular clusters are the only known stellar population that formed in essentially direct proportion to host galaxy halo mass.
• The intrinsic scatter in $\eta$ appears to be at most 0.2 dex; we argue that some of this scatter is due to differing degrees of tidal stripping of the globular cluster systems between central and satellite galaxies.