Non-gaussian mode coupling and the statistical cosmological principle

Marilena Loverde, Elliot Nelson, Sarah Shandera

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Local-type primordial non-Gaussianity couples statistics of the curvature perturbation ζ on vastly different physical scales. Because of this coupling, statistics (i.e. the polyspectra) of ζ in our Hubble volume may not be representative of those in the larger universe - that is, they may be biased. The bias depends on the local background value of ζ, which includes contributions from all modes with wavelength k ≲ H0 and is therefore enhanced if the entire post-inflationary patch is large compared with our Hubble volume. We study the bias to locally-measured statistics for general local-type non-Gaussianity. We consider three examples in detail: (i) the usual fNL, gNL model, (ii) a strongly non-Gaussian model with ζ ∼ ζpG, and (iii) two-field non-Gaussian initial conditions. In each scenario one may generate statistics in a Hubble-size patch that are weakly Gaussian and consistent with observations despite the fact that the statistics in the larger, post-inflationary patch look very different.

Original languageEnglish (US)
Article number024
JournalJournal of Cosmology and Astroparticle Physics
Issue number6
StatePublished - Jun 2013

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics


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