GLOBULAR-CLUSTER SYSTEMS FORMED IN GALAXY MERGERS

We show that current observations support the hypothesis that globular clusters form in galaxy mergers. In a previous paper, we presented a model in which globular cluster formation is a result of interactions and mergers of galaxies. Here, this model is compared with new observa tions of the globular cluster systems of recent galaxy mergers and nor mal elliptical galaxies. We find that our model is consistent with the number and luminosity of young globular clusters in currently merging galaxies. If elliptical galaxies form through mergers of spiral galax ies, the model also predicts that the globular cluster systems of norm al elliptical galaxies should have at least two peaks in the metallici ty distribution. We show that observations of the globular cluster sys tems of nearby elliptical galaxies support this prediction. More gener ally, the presence of more than one peak in the globular cluster metal licity distribution strongly argues against a single formation epoch f or globular clusters in elliptical galaxies. Instead, these observatio ns favour formation models in which globular clusters form in two or m ore bursts, as is the case in our merging model.