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arXiv · 1305.0813

Hemispherical Asymmetry and Local non-Gaussianity: a Consistency Condition

Mohammad Hossein Namjoo·Shant Baghram·Hassan Firouzjahi
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Abstract

In this paper we provide a consistency relation between the amplitude of the hemispherical bipolar asymmetry, $A$, and the amplitude of the primordial non-Gaussianity in the squeezed limit, $f_{NL}$, as $|A| \lesssim 10^{-1} f_{NL}$. We demonstrate that this consistency condition is at work for any model of inflation in which the curvature perturbations is sourced by a single light field with the Bunch-Davies initial condition, irrespective of the number of inflation fields which contribute to the background inflationary expansion. As a non-trivial example, we show that observable hemispherical asymmetry can be generated in single field non-attractor inflationary models. We also study hemispherical asymmetry generated in the models of multiple fields inflation. We show that $A$ is controlled by the weighted sum of non-Gaussianity contribution from each field. In particular, we show that observable hemispherical asymmetry can be generated in models where inhomogeneities are generated from a light scalar field modulating the surface of end of inflation.

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Mohammad Hossein Namjoo, Shant Baghram, Hassan Firouzjahi. 2013-05-16. Hemispherical Asymmetry and Local non-Gaussianity: a Consistency Condition. https://doi.org/10.1103/physrevd.88.083527

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