Creating statistically anisotropic and inhomogeneous perturbations

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Abstract

In almost all structure formation models, primordial perturbations are created within a homogeneous and isotropic universe, like the one we observe. Because their ensemble averages inherit the symmetries of the spacetime in which they are seeded, cosmological perturbations then happen to be statistically isotropic and homogeneous. Certain anomalies in the cosmic microwave background on the other hand suggest that perturbations do not satisfy these statistical properties, thereby challenging perhaps our understanding of structure formation. In this paper we relax this tension. We show that if the universe contains an appropriate triad of scalar fields with spatially constant but non-zero gradients, it is possible to generate statistically anisotropic and inhomogeneous primordial perturbations, even though the energy-momentum tensor of the triad itself is invariant under translations and rotations.

Original languageEnglish (US)
Article number014
JournalJournal of Cosmology and Astroparticle Physics
Issue number9
DOIs
StatePublished - Sep 1 2007

Keywords

  • Cosmological perturbation theory
  • Inflation
  • Physics of the early universe

ASJC Scopus subject areas

  • Astronomy and Astrophysics

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