Residual gas expulsion from young globular clusters

Abstract

The results of N-body simulations of the expulsion of residual gas from young globular clusters are presented. Globular clusters with a variety of initial masses, Galactocentric radii, concentration and initial mass function slope with star formation efficiencies (SFEs) below 50% were investigated. The residual gas in the clusters was simply treated as an external potential acting upon the star particles which was reduced in a number of ways to simulate the loss of the gas. The states of the clusters after ~50 Myr was compared to the results of Chernoff & Shapiro (1987) in order to estimate if the clusters would be able to survive for a Hubble time or would be disrupted. The rapid expulsion of large amounts of a cluster's initial mass is found to considerably effect the structures of clusters, but they may be able to survive with SFEs far lower than 50%. It is suggested that the Galactic globular cluster population could have formed from a proto-cluster populations with SFEs ~40% and central densities approximately the same as those found in giant molecular clouds.