Core collapse with strong encounters

This paper explores the possibility that close two-body encounters, though normally unimportant for the evolution of systems of point masses, may be important in the late stages of core collaspe when fewer than 100 particles remain in the core. An orbit-averaged integral equation in energy space is given for the time development of the system, on the assumption that all particles have the same mass and that their distribution function is isotropic. The equation reduces to the orbit-averaged Fokker-Planck equation in the limit of weak encounters. Numerical computations based on this equation are reported. The results show that the evolution due to strong encounters is very similar to that due to numerous weak ones, except for the evaporation rate.

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