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

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.

8 pages, 6 figures, extended discussion of level of isotropy, matches version accepted in ApJ

Cited by in corpus (11)

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• Improved two-point correlation function estimates using glass-like distributions as a reference sample
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• Impacts of pre-initial conditions on anisotropic separate universe simulations: a boosted tidal response in the epoch of reionization
• Glass-Like Random Catalogues for Two-Point Estimates on the Light Cone
• Particle loads for cosmological simulations with equal-mass dark matter and baryonic particles