Direct Fokker-Planck Calculations

Abstract

The past decade has seen the development of powerful numerical methods for studying star cluster evolution by direct integration of the Fokker-Planck equation. Cohn's basic algorithm for spherical systems of identical point masses and its application to the study of core collapse is reviewed. Merritt's extension of this method to treat systems containing a mass spectrum, and Goodman's extensions to include strong scattering and rotation are discussed. Results from direct Fokker-Planck computations of core collapse in single mass and multi-mass isotropic clusters and single mass anisotropic clusters are presented to illustrate the method. Calculations of pre- and post-collapse evolution with a central black hole and with heating by hard binaries are reported. Prospects for future development of the direct Fokker-Planck method will be discussed, with emphasis on the central goal of developing physically realistic models for interpreting Hubble Space Telescope observations of globular cluster structure.