title: Cosmic microwave background 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 power spectrum. This provides an alternative origin for a power asymmetry that 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 cosmic microwave background power asymmetry place stringent constraints on the duration of inflation in such models.
authors: Theoretical Astrophysics, California Institute of Technology, Mail Code 350-17, Pasadena, California 91125, USA.
authors: Fabian
authors: F
authors: Schmidt
authors: Lam
authors: L
authors: Hui