2022MNRAS.513.2609Z

Using a new method to estimate total galaxy mass (M_T) and two samples of low-luminosity galaxies containing measurements of the number of globular clusters (GCs) per galaxy (N_GC), we revisit the N_GC-M_T relation using a total of 203 galaxies, 157 of which have M_T ≤ 10¹⁰ M_⊙. We find that the relation is nearly linear, N_GC ∝ M_T^0.92 ± 0.08^ down to at least M_T ∼ 10^8.75 M_⊙. Because the relationship extends to galaxies that average less than one GC per galaxy and to a mass range in which mergers are relatively rare, the relationship cannot be solely an emergent property of hierarchical galaxy formation. The character of the radial GC distribution in low-mass galaxies, and the lack of mergers at these galaxy masses, also appears to challenge models in which the GCs form in central, dissipatively concentrated high-density, high-pressure regions and are then scattered to large radius. The slight difference between the fitted power-law exponent and a value of one leaves room for a shallow M_T-dependent variation in the mean mass per GC that would allow the relation between total mass in GCs and M_T to be linear.