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N-Body Growth of a Bahcall-Wolf Cusp Around a Black Hole

Miguel Preto·David Merritt·Rainer Spurzem
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Abstract

We present a clear N-body realization of the growth of a Bahcall-Wolf f ~ E^0.25 (rho ~ 1/r^1.75) density cusp around a massive object ("black hole") at the center of a stellar system. Our N-body algorithm incorporates a novel implementation of Mikkola-Aarseth chain regularization to handle close interactions between star and black hole particles. Forces outside the chain were integrated on a GRAPE-6A/8 special-purpose computer with particle numbers up to N=0.25 x 10^6. We compare our N-body results with predictions of the isotropic Fokker-Planck equation and verify that the time dependence of the density (both configuration and phase-space) predicted by the Fokker-Planck equation is well reproduced by the N-body algorithm, for various choices of N and of the black hole mass. Our results demonstrate the feasibility of direct-force integration techniques for simulating the evolution of galactic nuclei on relaxation time scales.

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Miguel Preto, David Merritt, Rainer Spurzem. 2004-07-09. N-Body Growth of a Bahcall-Wolf Cusp Around a Black Hole. https://doi.org/10.1086/425139

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