On the effects of dynamical evolution on the initial mass function of globular 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, stellar evolution and disc shocking, and including the effects of the tidal held of the Galaxy. We investigate the evolution of multi-mass models with a power-law initial mass function (IMF) starting with different initial masses, concentrations, slopes of the IMF and located at different, galactocentric distances. We show to what extent the effects of the various evolutionary processes alter the shape of the IMF and to what extent these changes depend on the position of the cluster in the Galaxy. The changes in both the global and the local mass functions (measured at different distances from the cluster centre) are investigated, showing whether and where the local mass function keeps memory of the IMF and where it provides a good indication of the current global mass function. The evolution of the population of white dwarfs is also followed in detail, and we supply an estimate of the fraction of the current value of the total mass expected to be in white dwarfs depending on the main initial conditions for the cluster (mass and position in the Galaxy). Simple analytical expressions have been derived by which it is possible to calculate the main quantities of interest (total mass, fraction of white dwarfs, slope of the mass function) at any time t for a larger number of different initial conditions than those investigated numerically.