Erosion of globular cluster systems: the influence of radial anisotropy, central black holes and dynamical friction

We present the adaptable muesli code for investigating dynamics and erosion processes of globular clusters (GCs) in galaxies. Muesli follows the orbits of individual clusters and applies internal and external dissolution processes to them. Orbit integration is based on the self-consistent field method in combination with a time-transformed leapfrog scheme, allowing us to handle velocity-dependent forces like triaxial dynamical friction. In a first application, the erosion of GC systems (GCSs) in elliptical galaxies is investigated. Observations show that massive ellipticals have rich, radially extended GCSs, while some compact dwarf ellipticals contain no GCs at all. For several representative examples, spanning the full mass scale of observed elliptical galaxies, we quantify the influence of radial anisotropy, galactic density profiles, supermassive black holes and dynamical friction on the GC erosion rate. We find that GC number density profiles are centrally flattened in less than a Hubble time, naturally explaining observed cored GC distributions. The erosion rate depends primarily on a galaxy's mass, half-mass radius and radial anisotropy. The fraction of eroded GCs is nearly 100 per cent in compact, M32-like galaxies and lowest in extended and massive galaxies. Finally, we uncover the existence of a violent tidal-disruption-dominated phase which is important for the rapid build-up of halo stars.