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Title: Cosmic variance of the spectral index from mode coupling

We demonstrate that local, scale-dependent non-Gaussianity can generate cosmic variance uncertainty in the observed spectral index of primordial curvature perturbations. In a universe much larger than our current Hubble volume, locally unobservable long wavelength modes can induce a scale-dependence in the power spectrum of typical subvolumes, so that the observed spectral index varies at a cosmologically significant level (|Δn{sub s}| ∼ O(0.04)). Similarly, we show that the observed bispectrum can have an induced scale dependence that varies about the global shape. If tensor modes are coupled to long wavelength modes of a second field, the locally observed tensor power and spectral index can also vary. All of these effects, which can be introduced in models where the observed non-Gaussianity is consistent with bounds from the Planck satellite, loosen the constraints that observations place on the parameters of theories of inflation with mode coupling. We suggest observational constraints that future measurements could aim for to close this window of cosmic variance uncertainty.
Authors:
;  [1] ; ;  [2]
  1. Department of Physics and Astronomy, University of Hawaii, 2505 Correa Rd., Honolulu HI (United States)
  2. Institute for Gravitation and the Cosmos, The Pennsylvania State University, University Park, PA 16802 (United States)
Publication Date:
OSTI Identifier:
22369934
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2013; Journal Issue: 11; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COUPLING; LIMITING VALUES; SATELLITES; SHAPE; SPECTRA; TENSORS; UNIVERSE; WAVELENGTHS