Einstein's signature in cosmological large-scale structure

Marco Bruni*, Juan Carlos Hidalgo, David Wands

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

We show how the nonlinearity of general relativity generates a characteristic nonGaussian signal in cosmological large-scale structure that we calculate at all perturbative orders in a large-scale limit. Newtonian gravity and general relativity provide complementary theoretical frameworks for modeling large-scale structure in ΛCDM cosmology; a relativistic approach is essential to determine initial conditions, which can then be used in Newtonian simulations studying the nonlinear evolution of the matter density. Most inflationary models in the very early universe predict an almost Gaussian distribution for the primordial metric perturbation, ζ. However, we argue that it is the Ricci curvature of comoving-orthogonal spatial hypersurfaces, R, that drives structure formation at large scales. We show how the nonlinear relation between the spatial curvature, R, and the metric perturbation, ζ, translates into a specific nonGaussian contribution to the initial comoving matter density that we calculate for the simple case of an initially Gaussian ζ. Our analysis shows the nonlinear signature of Einstein's gravity in large-scale structure.

Original languageEnglish
Article numberL11
Pages (from-to)L11
JournalAstrophysical Journal Letters
Volume794
Issue number1
DOIs
Publication statusPublished - 10 Oct 2014

Keywords

  • dark matter
  • large-scale structure of universe
  • RCUK
  • STFC
  • ST/K00090X/1 and ST/L005573/1

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