2013/03/31 by Marilena LoVerde, Elliot Nelson, Sarah Shandera
Physics and Astronomy · #Cosmological perturbation theory #Cosmology #Cosmology and Gravitation Theories #Coupling (piping) #Dark energy #Galaxies: Formation, Evolution, Phenomena #Gaussian #Hubble volume #Hubble's law #Non-Gaussianity #Statistical Mechanics and Entropy #Universe #astro-ph.CO #hep-th
paper · pdf · doi:10.1088/1475-7516/2013/06/024
published as JCAP 06, 024 (2013) · 34 pages, 8 Figures. references added, typos corrected; v3 matches JCAP version
arxiv created 2013/06/17 · openalex publication_date 2013/06/19 · arxiv updated 2015/06/15 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
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 ≲ H 0 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 f NL , g NL model, (ii) a strongly non-Gaussian model with ζ ∼ ζ G p , 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.