PIRSA:13100076

A Nearly Gaussian Hubble-patch in a non-Gaussian Universe

LoVerde, M. (2013). A Nearly Gaussian Hubble-patch in a non-Gaussian Universe. Perimeter Institute. https://pirsa.org/13100076

LoVerde, Marilena. A Nearly Gaussian Hubble-patch in a non-Gaussian Universe. Perimeter Institute, Oct. 08, 2013, https://pirsa.org/13100076 

          @misc{ pirsa_PIRSA:13100076,
            doi = {10.48660/13100076},
            url = {https://pirsa.org/13100076},
            author = {LoVerde, Marilena},
            keywords = {Cosmology},
            language = {en},
            title = {A Nearly Gaussian Hubble-patch in a non-Gaussian Universe},
            publisher = {Perimeter Institute},
            year = {2013},
            month = {oct},
            note = {PIRSA:13100076 see, \url{https://pirsa.org}}
          }

Marilena LoVerde University of Washington

DOI 10.48660/13100076
Collection
Talk Type Scientific Series
Subject

Abstract

Local-type primordial non-Gaussianity couples statistics of the curvature perturbation \zeta on vastly different physical scales. Because of this coupling, statistics (i.e. the polyspectra) of \zeta 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 \zeta, 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. I will discuss the bias to locally-measured statistics for general local-type non-Gaussianity. I will discuss three examples in detail: (i) the usual fNL, gNL model, (ii) a strongly non-Gaussian model with \zeta ~ \zeta_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. Finally, I will present a worked example of how the variation in local statistics arises in the curvaton scenario.