Space-Dependent Step Features: Transient Breakdown of Slow-roll, Homogeneity and Isotropy During Inflation

Abstract

A step feature in the inflaton potential can model a transient breakdown of slow-roll inflation. Here we generalize the step feature to include space-dependence, allowing it also to model a breakdown of homogeneity and isotropy. The space-dependent inflaton potential generates a classical curvature perturbation mode characterized by the wavenumber of the step inhomogeneity. For inhomogeneities small compared with the horizon at the step, space-dependence has a small effect on the curvature perturbation. Therefore the smoothly oscillating quantum power spectrum predicted by the homogeneous step is robust with respect to sub-horizon space-dependence. For inhomogeneities equal to or greater than the horizon at the step, the space-dependent classical mode can dominate, producing a curvature perturbation in which modes of wavenumber determined by the step inhomogeneity are superimposed on the oscillating power spectrum. Generation of a space-dependent step feature may therefore provide a mechanism to introduce primordial anisotropy into the curvature perturbation. Space-dependence also modifies the quantum fluctuations, in particular via resonance-like features coming from mode coupling to amplified superhorizon modes. However these effects are small relative to the classical modes.

10 pages, 9 figures, minor text alterations, published version

References in corpus (10)

• Generation and Characterization of Large Non-Gaussianities in Single Field Inflation
• Hemispherical power asymmetry in the three-year Wilkinson Microwave Anisotropy Probe sky maps
• A Hemispherical Power Asymmetry from Inflation
• Inflation and WMAP three year data: Features have a Future!
• Superhorizon Perturbations and the Cosmic Microwave Background
• New Universal Local Feature in the Inflationary Perturbation Spectrum
• New Constraints on Oscillations in the Primordial Spectrum of Inflationary Perturbations
• The pre-inflationary vacuum in the cosmic microwave background
• Testable polarization predictions for models of CMB isotropy anomalies
• Curvatons and inhomogeneous scenarios with deviation from slow-roll

Cited by in corpus (11)

• Particle Production During Inflation: Observational Constraints and Signatures
• On Features and Nongaussianity from Inflationary Particle Production
• Reconstruction of the Primordial Power Spectrum using Temperature and Polarisation Data from Multiple Experiments
• Reconstruction of the primordial power spectrum of curvature perturbations using multiple data sets
• Reconstruction of the Primordial Power Spectrum by Direct Inversion
• A Multiple Step-like Spectrum of Primordial Perturbation
• Phantom Inflation with A Steplike Potential
• Primordial Power Spectrum features and $f_{NL}$ constraints
• PRISM: Sparse Recovery of the Primordial Power Spectrum
• Large Scale Structure Forecast Constraints on Particle Production During Inflation
• Can Relic Superhorizon Inhomogeneities be Responsible for Large-Scale CMB Anomalies?