Scale-dependent hemispherical asymmetry from general initial state during inflation

TL;DR

This paper proposes a model where a general initial state during inflation causes a scale-dependent hemispherical asymmetry, with observable signatures in non-Gaussianity and potential oscillatory features detectable in CMB data.

Contribution

It introduces a novel mechanism linking non-vacuum initial states to scale-dependent hemispherical asymmetry and predicts specific observational signatures.

Findings

Dipole asymmetry amplitude decreases exponentially on small scales.

Oscillatory features in asymmetry can be detected in CMB maps.

Non-vacuum initial states naturally enhance super-horizon perturbations.

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.