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Sep 7 – 11, 2015
Warsaw, Poland
Europe/Zurich timezone

Oscillations in the CMB bispectrum

Sep 8, 2015, 4:30 PM
20m
Main Hall

Main Hall

Speaker

Moritz Munchmeyer (Universite Pierre et Marie Curie, Institute Astrophysique de Paris, France)

Description

Oscillating signatures in the correlation functions of the primordial density perturbations are predicted by a variety of inflationary models. A theoretical mechanism that has attracted much attention is a periodic shift symmetry as implemented in axion monodromy inflation. This symmetry leads to resonance non-gaussianities, whose key feature are logarithmically stretched oscillations. Oscillations are also a generic consequence of excited states during inflation and of sharp features in the potential. Oscillating shapes are therefore a very interesting experimental target. After giving an overview of these motivations, I will discuss how to search for these signatures in the CMB. Fast oscillations are difficult to search for with traditional estimation techniques, and I will demonstrate how targeted expansions, that exploit the symmetry properties of the shapes, allow to circumvent these difficulties. As a member of the Planck collaboration, I will discuss the Planck results that have been obtained using these methods in the bispectrum, as well as a joint search using bispectrum and power spectrum. Due to their low overlap with other non-gaussian shapes, oscillating bispectrum shapes are not exhaustively constrained and a potential discovery is therefore not yet ruled out. My talk will be based in particular on arxiv:1412.3461, arxiv:1505.05882 and Planck publications on inflation and non-gaussianities.

Presentation materials