MULTIVARIATE-ANALYSIS OF GLOBULAR-CLUSTER SYSTEMS IN EARLY-TYPE GALAXIES

We use multivariate statistical analysis to study the relation between the globular cluster content of early-type galaxies and a number of t heir observed properties. The number of globular clusters scales non-l inearly with galaxy luminosity and virial mass. Both the total number of clusters and their specific frequency correlate with metallicity, i nternal velocity anisotropy, isophotal shape parameters and, possibly, X-ray luminosity of the host galaxy. We observe that the properties o f the globular cluster systems, to a large extent, are correlated with the so-called Fundamental Plane of early-type galaxies, although a re sidual amount of variability in the number and specific frequency of g lobulars remains. This residual scatter correlates with the variables which reflect velocity anisotropy and isophotal shape. These results i mply that the mechanisms of formation of the globular clusters are clo sely tied to those operating during the formation and evolution of the ir host galaxies. We also briefly investigate the properties of globul ar cluster systems in low surface brightness dwarf galaxies and compar e them to those of large ellipticals. Possible theoretical implication s of our results are discussed and we conclude that the formation of g lobular clusters in early-type galaxies was, at least partially, drive n by dissipative interactions and merging, most of which possibly took place at early epochs.