Figure 6

Half-mass and Core Radii of Idealized Clusters—The half-mass and core radii, averaged over 100 dynamical times, for all four models as determined by direct N-body (NBODY6, in black), the Monte Carlo (CMC, in blue), and the hybrid approach (RAPID, in red). We only show one realization from NBODY6, while we show 10 realizations each for CMC and RAPID RAPID reproduces both the core and half-mass radii at early times better that CMC (with the exception of the 64k-0.01-10 run, though RAPID is still much closer than CMC). On the other hand, RAPID reproduces the core radii of the full N-body runs far more accurately than CMC, with the core radii from NBODY6 and CMC disagreeing by up to a factor of 3. At late times, the core radii from RAPID begins to diverge from NBODY6; this occurs when the majority of the BH system has been ejected, and the CMC-controlled two-body relaxation dominates the BH dynamics. RAPID reverts to pure CMC when the number of BHs drops below a certain threshold (5 BHs, indicated by the black dashed lines, (with the gray bands indicating the 1σ variation across the 10 runs)