GLOBULAR CLUSTER POPULATIONS: RESULTS INCLUDING S 4 G LATE-TYPE GALAXIES

Using 3.6 and 4.5 μ m images of 73 late-type, edge-on galaxies from the S 4 G survey, we compare the richness of the globular cluster populations of these galaxies to those of early-type galaxies that we measured previously. In general, the galaxies presented here fill in the distribution for galaxies with lower stellar mass, M * , specifically , overlap the results for early-type galaxies of similar masses, and, by doing so, strengthen the case for a dependence of the number of globular clusters per 10 9 M ⊙ of galaxy stellar mass, T N , on M * . For we find the relationship can be satisfactorily described as when M * is expressed in solar masses. The functional form of the relationship is only weakly constrained, and extrapolation outside this range is not advised. Our late-type galaxies, in contrast to our early types, do not show the tendency for low-mass galaxies to split into two T N families. Using these results and a galaxy stellar mass function from the literature, we calculate that, in a volume-limited, local universe sample, clusters are most likely to be found around fairly massive galaxies ( M * ∼ 10 10.8 M ⊙ ) and present a fitting function for the volume number density of clusters as a function of parent-galaxy stellar mass. We find no correlation between T N and large-scale environment, but we do find a tendency for galaxies of fixed M * to have larger T N if they have converted a larger proportion of their baryons into stars.