ON THE EFFECTS OF DYNAMICAL EVOLUTION ON THE INITIAL MASS FUNCTION OFGLOBULAR-CLUSTERS

In this paper we show the results of a large set of N-body simulations modelling the evolution of globular clusters driven by relaxation, st ellar evolution and disc shocking, and including the effects of the ti dal held of the Galaxy. We investigate the evolution of multi-mass mod els with a power-law initial mass function (IMF) starting with differe nt initial masses, concentrations, slopes of the IMF and located at di fferent, galactocentric distances. We show to what extent the effects of the various evolutionary processes alter the shape of the IMF and t o what extent these changes depend on the position of the cluster in t he Galaxy. The changes in both the global and the local mass functions (measured at different distances from the cluster centre) are investi gated, showing whether and where the local mass function keeps memory of the IMF and where it provides a good indication of the current glob al mass function. The evolution of the population of white dwarfs is a lso followed in detail, and we supply an estimate of the fraction of t he current value of the total mass expected to be in white dwarfs depe nding on the main initial conditions for the cluster (mass and positio n in the Galaxy). Simple analytical expressions have been derived by w hich it is possible to calculate the main quantities of interest (tota l mass, fraction of white dwarfs, slope of the mass function) at any t ime t for a larger number of different initial conditions than those i nvestigated numerically.