Destruction of the Galactic Globular Cluster System

Abstract

We investigate the dynamical evolution of the Galactic Globular Cluster System in considerably greater detail than has been done hitherto, finding that destruction rates are significantly larger than given by previous estimates. More than half of the present clusters (52%-58% for the OC galactic model, and 75%-86% for the BSS model) will be destroyed in the next Hubble time. For the evolution of individual clusters we use a Fokker-Planck code including two-body relaxation, tidal truncation of clusters, compressive gravitational shocks while clusters pass through the Galactic disk, and tidal shocks due to passage close to the bulge. Gravitational shocks are treated comprehensively, using a recent result by Kundic & Ostriker (1995) that the shock-induced relaxation term, driving an additional dispersion of energies, is generally more important than the usual energy shift term. We discuss some implications for a past history of the Globular Cluster System, and the initial distribution of the destruction times raising the possibility that the current population is but a very small fraction of the initial population with the remnants of the destroyed clusters constituting presently a large fraction of the spheroid (bulge+halo) stellar population.