Dark energy perturbations in N-body simulations

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  • Jeppe Dakin
  • ,
  • Steen Hannestad
  • Thomas Tram
  • ,
  • Mischa Knabenhans, Physik-Institut, Universitat Zürich-Irchel
  • ,
  • Joachim Stadel, Physik-Institut, Universitat Zürich-Irchel

We present N-body simulations which are fully compatible with general relativity, with dark energy consistently included at both the background and perturbation level. We test our approach for dark energy parameterised as both a fluid, and using the parameterised post-Friedmann (PPF) formalism. In most cases, dark energy is very smooth relative to dark matter so that its leading effect on structure formation is the change to the background expansion rate. This can be easily incorporated into Newtonian N-body simulations by changing the Friedmann equation. However, dark energy perturbations and relativistic corrections can lead to differences relative to Newtonian N-body simulations at the tens of percent level for scales k < (10-3-10-2) Mpc-1, and given the accuracy of upcoming large scale structure surveys such effects must be included. In this paper we will study both effects in detail and highlight the conditions under which they are important. We also show that our N-body simulations exactly reproduce the results of the Boltzmann solver CLASS for all scales which remain linear.

Original languageEnglish
Article number013
JournalJournal of Cosmology and Astroparticle Physics
Issue8
Number of pages19
ISSN1475-7516
DOIs
Publication statusPublished - 12 Aug 2019

    Research areas

  • cosmological simulations, dark energy theory, dark matter simulations, power spectrum

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