Methods 435Table 15.2.Parameters of the numerical simulations.
Softening Steps
Simulation (h−^1 kpc) Dyn. range (min–max) Nsteps/dyn. range
AP^3 M 1 3.5 4267 8000 1.87
AP^3 M 2 2.3 6400 6000 0.94
AP^3 M 3 1.8 8544 6000 0.70
AP^3 M 4 3.5 4267 2000 0.47
AP^3 M 5 7.0 2133 8000 3.75
ART 1 3.7 4096 660–21 120 2.58
ART 2 3.7 4096 330–10 560 5.16Figure 15.5. The correlation function of dark matter particles. Note that the range of
correlation amplitudes is different in the inset panel.
correlation amplitude deviates less than that of the AP^3 M 3 run indicates that the
effect is very sensitive to the force resolution.
Note that the AP^3 M 3 run has formally the best force resolution. Thus, one
would naively expect that it would give the largest correlation function. At scales
. 30 h−^1 kpc the deviations of the AP^3 M 3 from the ART 1 or the AP^3 M 5 runs
are≈100–200%. We attribute these deviations to the numerical effects: the high
force resolution in AP^3 M 3 was not adequately supported by the time integration.
In other words, the AP^3 M 3 had too few time steps. Note that it had quite a large