Séminaire / Seminar GReCO |
| « Non-Gaussianity and New Probes of Spatial Curvature » |
|
Sadra Jazayeri |
|
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 ?at background geometry. Given that direct measurements of ?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 ?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 ?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 ?k. In addition, we compute the modi?cation of the bispectrum up to leading order in ?k, 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 ?nd that there are no adiabatic modes and therefore soft theorems, such as the consistency relation of Maldacena, are generally violated. |
|
lundi 18 novembre 2019 - 11:00 Salle des séminaires Évry Schatzman Institut d'Astrophysique de Paris |
| Pages web du séminaire / Seminar's webpage |