Optimal Softening for N-Body Halo Simulations

Abstract

We propose to determine the optimal softening length in N-body halo simulations by minimizing the ensemble-average acceleration error at a small radius r0. This strategy ensures that the error never exceeds the optimal value beyond r0. Furthermore, we derive semi-analytic formulae for calculating the acceleration error due to the discreteness of particles and softened gravity, which are validated by direct N-body force calculations. We estimate that current state-of-the-art halo simulations suffer >~6% acceleration error at 1% of the halo virial radius. The error grows rapidly toward the center and could contribute significantly to the uncertainties of inner halo properties.

4 pages, 4 figures, ApJ accepted, shortened the abstract, corrected a label in Fig. 2, results unchanged

References in corpus (5)

• The Inner Structure of LambdaCDM Halos III: Universality and Asymptotic Slopes
• The Inner Structure of LambdaCDM Halos I: A Numerical Convergence Study
• Earth-mass dark-matter haloes as the first structures in the early Universe
• Structure of Dark Matter Halos From Hierarchical Clustering. III. Shallowing of The Inner Cusp
• Evolution of the Cluster Correlation Function

Cited by in corpus (12)

• The fine-grained phase-space structure of Cold Dark Matter halos
• Evolution of spiral galaxies in modified gravity
• Discreteness Effects in Lambda Cold Dark Matter Simulations: A Wavelet-Statistical View
• Cosmic tomographies: baryon acoustic oscillations and weak lensing
• Constraints on WIMP and Sommerfeld-Enhanced Dark Matter Annihilation from HESS Observations of the Galactic Center
• On the isolated dwarf galaxies: from cuspy to flat dark matter density profiles and metallicity gradients
• The optimal gravitational softening length for cosmological N-body simulations
• The effect of softening on dynamical simulations of galaxies
• Inner structure of dark matter halos at high $z$ in cosmological models with non-power-law primordial spectra
• Smooth halos in the cosmic web
• Numerical Study of Bar Suppression in Galaxy Models Due to Disc Heating
• Tidal adaptive softening and artificial fragmentation in cosmological simulations