Compactified cosmological simulations of the infinite universe

Gábor Rácz, I. Szapudi, I. Csabai, László Dobos

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

We present a novel N-body simulation method that compactifies the infinite spatial extent of the Universe into a finite sphere with isotropic boundary conditions to follow the evolution of the large-scale structure. Our approach eliminates the need for periodic boundary conditions, a mere numerical convenience which is not supported by observation and which modifies the law of force on large scales in an unrealistic fashion. We demonstrate that our method outclasses standard simulations executed on workstation-scale hardware in dynamic range, it is balanced in following a comparable number of high and low k modes and, its fundamental geometry and topology match observations. Our approach is also capable of simulating an expanding, infinite universe in static coordinates with Newtonian dynamics. The price of these achievements is that most of the simulated volume has smoothly varying mass and spatial resolution, an approximation that carries different systematics than periodic simulations. Our initial implementation of the method is called StePS which stands for Stereographically projected cosmological simulations. It uses stereographic projection for space compactification and naiveO(N2) force calculationwhich is nevertheless faster to arrive at a correlation function of the same quality than any standard (tree or P3M) algorithm with similar spatial and mass resolution. The N2 force calculation is easy to adapt to modern graphics cards, hence our code can function as a high-speed prediction tool for modern large-scale surveys. To learn about the limits of the respective methods, we compare StePS with GADGET-2 running matching initial conditions.

Original languageEnglish
Pages (from-to)1949-1957
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Volume477
Issue number2
DOIs
Publication statusPublished - Jun 21 2018

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universe
simulation
boundary condition
spatial resolution
stereographic projection
boundary conditions
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hardware
topology
dynamic range
projection
high speed
geometry
method
prediction
predictions
approximation

Keywords

  • Dark matter
  • Large-scale structure of Universe
  • Methods: Numerical

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Compactified cosmological simulations of the infinite universe. / Rácz, Gábor; Szapudi, I.; Csabai, I.; Dobos, László.

In: Monthly Notices of the Royal Astronomical Society, Vol. 477, No. 2, 21.06.2018, p. 1949-1957.

Research output: Contribution to journalArticle

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