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Classical and Quantum Gravity 28, 22 (2011) 222001
Hunting for Isocurvature Modes in the CMB non-Gaussianities
D. Langlois1, 2, Bartjan Van Tent3

We investigate new shapes of local primordial non-Gaussianities in the CMB. Allowing for a primordial isocurvature mode along with the main adiabatic one, the angular bispectrum is in general a superposition of six distinct shapes: the usual adiabatic term, a purely isocurvature component and four additional components that arise from correlations between the adiabatic and isocurvature modes. We present a class of early Universe models in which various hierarchies between these six components can be obtained, while satisfying the present upper bound on the isocurvature fraction in the power spectrum. Remarkably, even with this constraint, detectable non-Gaussianity could be produced by isocurvature modes. We finally discuss the prospects of detecting these new shapes with the Planck satellite.
1 :  APC - UMR 7164 - AstroParticule et Cosmologie
2 :  IAP - Institut d'Astrophysique de Paris
3 :  LPT - Laboratoire de Physique Théorique d'Orsay [Orsay]
Physique/Relativité Générale et Cosmologie Quantique

Physique/Physique des Hautes Energies - Théorie
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