Power Spectrum and Non-Gaussianities in Anisotropic Inflation

Abstract

We study the planar regime of curvature perturbations for single field inflationary models in an axially symmetric Bianchi I background. In a theory with standard scalar field action, the power spectrum for such modes has a pole as the planarity parameter goes to zero. We show that constraints from back reaction lead to a strong lower bound on the planarity parameter for high-momentum planar modes and use this bound to calculate the signal-to-noise ratio of the anisotropic power spectrum in the CMB, which in turn places an upper bound on the Hubble scale during inflation allowed in our model. We find that non-Gaussianities for these planar modes are enhanced for the flattened triangle and the squeezed triangle configurations, but show that the estimated values of the f_NL parameters remain well below the experimental bounds from the CMB for generic planar modes (other, more promising signatures are also discussed). For a standard action, f_NL from the squeezed configuration turns out to be larger compared to that from the flattened triangle configuration in the planar regime. However, in a theory with higher derivative operators, non-Gaussianities from the flattened triangle can become larger than the squeezed configuration in a certain limit of the planarity parameter.

26 pages, 2 figures; version published in JCAP

References in corpus (13)

• Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift Universe
• Observational Signatures and Non-Gaussianities of General Single Field Inflation
• Generation and Characterization of Large Non-Gaussianities in Single Field Inflation
• Enhanced Non-Gaussianity from Excited Initial States
• Inflationary perturbations in anisotropic backgrounds and their imprint on the CMB
• The Fast Fourier Transform Telescope
• Science with a lunar low-frequency array: from the dark ages of the Universe to nearby exoplanets
• 21-cm Background Anisotropies Can Discern Primordial Non-Gaussianity
• Non-Gaussianity Consistency Relations, Initial States and Back-reaction
• Gravity Waves Signatures from Anisotropic pre-Inflation
• Background reionization history from omniscopes
• An analytic approach to perturbations from an initially anisotropic universe
• Astrophysics Conducted by the Lunar University Network for Astrophysics Research (LUNAR) and the Center for Lunar Origins (CLOE)

Cited by in corpus (8)

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• Hamiltonian theory of classical and quantum gauge invariant perturbations in Bianchi I spacetimes
• The Initial State of a Primordial Anisotropic Stage of Inflation
• Gravitational waves in Kasner spacetimes and Rindler wedges in Regge-Wheeler gauge: Unruh effect
• CMB statistical anisotropies of classical and quantum origins
• A comprehensive study of Modulation effects on CMB Polarization
• Probing pre-inflationary anisotropy with directional variations in the gravitational wave background
• A quantisation procedure in the presence of an initial Kasner singularity: primordial gravitational waves from triaxially anisotropic pre-inflation