Pantheon SEMPARIS Le serveur des séminaires parisiens Paris

Status Confirmed
Seminar Series SEM-GRECO
Subjects astro-ph
Date Monday 18 November 2019
Time 11:00
Institute IAP
Seminar Room Salle des séminaires Évry Schatzman
Speaker's Last Name Jazayeri
Speaker's First Name Sadra
Speaker's Email Address
Speaker's Institution Dept. Applied Mathematics Theoretical Physics (DAMTP) (Cambridge, Royaume-Uni)
Title Non-Gaussianity and New Probes of Spatial Curvature
Abstract Cosmological observations have virtually saturated their maximum precision in determining the value of the spatial curvatures, and by far CMB and BAO data are consistent with a flat background geometry. Given that direct measurements of $\Omega$k will be unlikely to improve the current bounds in any foreseeable future, it is important to look out for indirect signals sensitive to a non-vanishing $\Omega$k. In this work, we inspect the interplay between non-gaussianity and the spatial curvature. We point out that in the presence of equilateral and orthogonal non-gaussianities, the consistency demands a new signal to exist already in the power spectrum. We study how this new signal can lead to improved constraints on $\Omega$k and non-gaussianity by looking at the measured low-ell` values of CMB TT multipoles, and we discuss the subtleties present in the perturbative treatment of $\Omega$k. In addition, we compute the modification of the bispectrum up to leading order in Ωk, and we present the observational bounds on the size of the signal in the squeezed and equilateral shapes of the three-point function. In passing, we study adiabatic modes in curved universes. We find that there are no adiabatic modes and therefore soft theorems, such as the consistency relation of Maldacena, are generally violated.
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