Why does Einasto profile index $n\sim 6$ occur so frequently?

Abstract

We consider the behavior of spherically symmetric Einasto halos composed of gravitating particles in the Fokker-Planck approximation. This approach allows us to consider the undesirable influence of close encounters in the N-body simulations more adequately than the generally accepted criteria. The Einasto profile with index $n\approx 6$ is a stationary solution of the Fokker-Planck equation in the halo center. There are some reasons to believe that the solution is an attractor. Then the Fokker-Planck diffusion tends to transform a density profile to the equilibrium one with the Einasto index $n\approx 6$. We suggest this effect as a possible reason why the Einasto index $n\approx 6$ occurs so frequently in the interpretation of N-body simulation results. The results obtained cast doubt on generally accepted criteria of N-body simulation convergence.

7 pages, 2 figures, Accepted to JCAP

References in corpus (6)

• Cold dark matter haloes in the Planck era: evolution of structural parameters for Einasto and NFW profiles
• The redshift dependence of the structure of massive LCDM halos
• Disruption of Dark Matter Substructure: Fact or Fiction?
• The real and apparent convergence of N-body simulations of the dark matter structures: is the Navarro-Frenk-White profile real?
• Cusps in the center of galaxies: a real conflict with observations or a numerical artefact of cosmological simulations?
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