ON THE ORIGIN OF GLOBULAR-CLUSTERS IN ELLIPTIC GALAXIES

We correlate the estimated total numbers of globular clusters in elliptical galaxies (N(gc)), and the numbers per unit luminosity (S(N), with a variety of observed properties of the host galaxies, using multivariate statistical analysis. The number of globular clusters scales roughly as L(bol)2, and the 3/2 power of dynamical mass: bigger galaxies were more efficient in producing globular clusters. Both N(gc) and S(N) are correlated with the so-called fundamental plane of elliptical galaxies, suggesting that the processes which determine global properties of ellipticals also largely determine their globular cluster content, although a considerable residual scatter remains. We find that the redder (presumably more metal-rich) galaxies tend to have more globular clusters, implying that a dissipative formation mechanism was involved. We also find that galaxies which have more anisotropic velocity distributions tend to have more clusters, suggesting that mergers may have been important in the production of globular clusters. The data are consistent with the picture of formation of ellipticals and their globular cluster systems primarly through dissipative merging, much of which may have happened at the early epochs.