Bayesian Limits on Primordial Isotropy Breaking

Abstract

It is often assumed that primordial perturbations are statistically isotropic, which implies, among other properties, that their power spectrum is invariant under rotations. In this article, we test this assumption by placing model-independent bounds on deviations from rotational invariance of the primordial spectrum. Using five-year WMAP cosmic microwave anisotropy maps, we set limits on the overall norm and the amplitude of individual components of the primordial spectrum quadrupole. We find that there is no significant evidence for primordial isotropy breaking, and that an eventually non-vanishing quadrupole has to be subdominant.

6 double-column pages, 2 figues and 2 tables. Uses REVTeX4

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• Ghost instabilities of cosmological models with vector fields nonminimally coupled to the curvature
• Instability of the ACW model, and problems with massive vectors during inflation
• Statistical anisotropy of the curvature perturbation from vector field perturbations
• Bianchi Type-$V$ cosmology in $f(R,T)$ gravity with $\Lambda (T)$
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• Weak-lensing by the large scale structure in a spatially anisotropic universe: theory and predictions
• CMB statistics in noncommutative inflation
• Inflaton Two-Point Correlation in the Presence of a Cosmic String
• Can Relic Superhorizon Inhomogeneities be Responsible for Large-Scale CMB Anomalies?
• An analytic approach to perturbations from an initially anisotropic universe
• Effective Field Theory of Anisotropic Inflation and Beyond
• CMB Angular Power Spectrum from Correlated Primordial Fluctuation
• Non-gaussianity and Statistical Anisotropy in Cosmological Inflationary Models
• CMB constraints on noncommutative geometry during inflation
• Higher order spectra from an initially anisotropic universe
• Evolution of cosmological event horizons in anisotropic universes