Hemispherical Power Asymmetry from Scale-Dependent Modulated Reheating

Abstract

We propose a new model for the hemispherical power asymmetry of the CMB based on modulated reheating. Non-Gaussianity from modulated reheating can be small enough to satisfy the bound from Planck if the dominant modulation of the inflaton decay rate is linear in the modulating field $\sigma$. $\sigma$ must then acquire a spatially-modulated power spectrum with a red scale-dependence. This can be achieved if the primordial perturbation of $\sigma$ is generated via tachyonic growth of a complex scalar field. Modulated reheating due to $\sigma$ then produces a spatially modulated and scale-dependent sub-dominant contribution to the adiabatic density perturbation. We show that it is possible to account for the observed asymmetry while remaining consistent with bounds from quasar number counts, non-Gaussianity and the CMB temperature quadupole. The model predicts that the adiabatic perturbation spectral index and its running will be modified by the modulated reheating component.

11 pages, references corrected

References in corpus (10)

• Hemispherical power asymmetry in the three-year Wilkinson Microwave Anisotropy Probe sky maps
• A Hemispherical Power Asymmetry from Inflation
• Primordial Curvature Fluctuation and Its Non-Gaussianity in Models with Modulated Reheating
• Superhorizon Perturbations and the Cosmic Microwave Background
• Constraints on cosmic hemispherical power anomalies from quasars
• A Scale-Dependent Power Asymmetry from Isocurvature Perturbations
• Non-isotropy in the CMB power spectrum in single field inflation
• Hemispherical Asymmetry and Local non-Gaussianity: a Consistency Condition
• CMB dipole asymmetry from a fast roll phase
• Isocurvature and Curvaton Perturbations with Red Power Spectrum and Large Hemispherical Asymmetry

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• Expected dipole asymmetry in CMB polarization
• The hemispherical asymmetry from a scale-dependent inflationary bispectrum
• CMB hemispherical asymmetry from non-linear isocurvature perturbations
• Scale-dependent CMB asymmetry from primordial configuration
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• Anisotropic cosmology and inflation from tilted Bianchi IX model
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• Primordial inhomogeneities from massive defects during inflation
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• Finslerian dipolar modulation of the CMB power spectra at scales $2<l<600$
• Hidden in the background: a local approach to CMB anomalies