Scale-dependent hemispherical asymmetry from general initial state during inflation

Abstract

We consider a general initial state for inflation as the mechanism for generating scale-dependent hemispherical asymmetry. An observable scale-dependent non-Gaussianity is generated that leads to observable hemispherical asymmetry from the super-horizon long mode modulation. We show that the amplitude of dipole asymmetry falls off exponentially on small angular scales which can address the absence of dipole asymmetry at these scales.In addition, depending on the nature of non-vaccum initial state, the amplitude of the dipole asymmetry has oscillatory features which can be detected in a careful CMB map analysis. Furthermore, we show that the non-vacuum initial state provides a natural mechanism for enhancing the super horizon long mode perturbation as required to generate the dipole asymmetry.

(v1) 16 pages, 3 figures; (v2) 17 pages, more clarifications, discussions and references, to appear in Journal of Cosmology and Astroparticle Physics

References in corpus (18)

• Observational Signatures and Non-Gaussianities of General Single Field Inflation
• Hemispherical power asymmetry in the three-year Wilkinson Microwave Anisotropy Probe sky maps
• Enhanced Non-Gaussianity from Excited Initial States
• A Hemispherical Power Asymmetry from Inflation
• Mass hierarchies and non-decoupling in multi-scalar field dynamics
• Power asymmetry in WMAP and Planck temperature sky maps as measured by a local variance estimator
• Heavy fields, reduced speeds of sound and decoupling during inflation
• Superhorizon Perturbations and the Cosmic Microwave Background
• Asymmetric Beams and CMB Statistical Anisotropy
• Constraints on cosmic hemispherical power anomalies from quasars
• The curvature perturbation in a box
• A Scale-Dependent Power Asymmetry from Isocurvature Perturbations
• Multifield DBI Inflation and Non-Gaussianities
• A Note on Calm Excited States of Inflation
• Broken Isotropy from a Linear Modulation of the Primordial Perturbations
• Non-isotropy in the CMB power spectrum in single field inflation
• A new method for calculating the primordial bispectrum in the squeezed limit
• On the squeezed limit of the bispectrum in general single field inflation

Cited by in corpus (4)

• Pre-inflationary primordial perturbations
• Expected dipole asymmetry in CMB polarization
• CMB hemispherical asymmetry from non-linear isocurvature perturbations
• Generating $\fnl$ at $\ell\lsim 60$