Non-gaussian mode coupling and the statistical cosmological principle

Marilena Loverde, Elliot Nelson, Sarah Shandera

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

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
Volume2013
Issue number6
DOIs
StatePublished - Jun 1 2013

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coupled modes
statistics
universe
curvature
perturbation
wavelengths

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics

Cite this

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abstract = "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.",
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Non-gaussian mode coupling and the statistical cosmological principle. / Loverde, Marilena; Nelson, Elliot; Shandera, Sarah.

In: Journal of Cosmology and Astroparticle Physics, Vol. 2013, No. 6, 024, 01.06.2013.

Research output: Contribution to journalArticle

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AU - Nelson, Elliot

AU - Shandera, Sarah

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AB - 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.

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