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An alternative to grids and glasses: Quaquaversal pre-initial conditions for N-body simulations

Steen H. Hansen·Oscar Agertz·Michael Joyce·Joachim Stadel·Ben Moore·Doug Potter
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Abstract

N-body simulations sample their initial conditions on an initial particle distribution, which for cosmological simulations is usually a glass or grid, whilst a Poisson distribution is used for galaxy models, spherical collapse etc. These pre-initial conditions have inherent correlations, noise due to discreteness and preferential alignments, whilst the glass distribution is poorly defined and computationally expensive to construct. We present a novel particle distribution which can be useful as a pre-initial condition for N-body simulations, using a simple construction based on a ``quaquaversal'' tiling of space. This distribution has little preferred orientation (i.e. is statistically isotropic), has a rapidly vanishing large scale power-spectrum (P(k) ~ k^4), and is trivial to create. It should be particularly useful for warm dark matter and cold collapse simulations.

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Steen H. Hansen, Oscar Agertz, Michael Joyce, Joachim Stadel, Ben Moore, Doug Potter. 2006-12-19. An alternative to grids and glasses: Quaquaversal pre-initial conditions for N-body simulations. https://doi.org/10.1086/510477

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