Anisotropic gaseous models of tidally limited star clusters: comparison with other methods

Abstract

We present new models of the evolution and dissolution of star clusters evolving under the combined influence of internal relaxation and external tidal fields, using the anisotropic gaseous model based on the Fokker-Planck approximation, and a new escaper loss cone model. This model borrows ideas from loss cones of stellar distributions near massive black holes, and describes physical processes related to escaping stars by a simple model based on two timescales and a diffusion process. We compare our results with those of direct $N$-body models and of direct numerical solutions of the orbit-averaged Fokker-Planck equation. For this comparative study we limit ourselves to idealized single point mass star clusters, in order to present a detailed study of the physical processes determining the rate of mass loss, core collapse and other features of the system's evolution. With the positive results of our study the path is now open in the future to use the computationally efficient gaseous models for future studies with more realism (mass spectrum, stellar evolution).