Résumé / Abstract Seminaire_GReCO
SÉMINAIRE DU GRECO

"Non-Gaussianity and New Probes of Spatial Curvature"

Sadra Jazayeri
Dept. Applied Mathematics Theoretical Physics (DAMTP) (Cambridge, Royaume-Uni)

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

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