CMB Power Asymmetry from Non-Gaussian Modulation
Abstract
Non-Gaussianity in the inflationary perturbations can couple observable scales to modes of much longer wavelength (even superhorizon), leaving as a signature a large-angle modulation of the observed cosmic microwave background (CMB) power spectrum. This provides an alternative origin for a power asymmetry which is otherwise often ascribed to a breaking of statistical isotropy. The non-Gaussian modulation effect can be significant even for typical ~10^{-5} perturbations, while respecting current constraints on non-Gaussianity, if the squeezed limit of the bispectrum is sufficiently infrared divergent. Just such a strongly infrared-divergent bispectrum has been claimed for inflation models with a non-Bunch-Davies initial state, for instance. Upper limits on the observed CMB power asymmetry place stringent constraints on the duration of inflation in such models.
Cite
@article{arxiv.1210.2965,
title = {CMB Power Asymmetry from Non-Gaussian Modulation},
author = {Fabian Schmidt and Lam Hui},
journal= {arXiv preprint arXiv:1210.2965},
year = {2013}
}
Comments
4+epsilon pages, 1 figure; v2: minor edits and references added, reflects PRL version in press