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Non-Gaussianity of Large-Scale Cosmic Microwave Background Anisotropies beyond Perturbation Theory

N. Bartolo·S. Matarrese·A. Riotto
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Abstract

We compute the fully non-linear Cosmic Microwave Background (CMB) anisotropies on scales larger than the horizon at last-scattering in terms of only the curvature perturbation, providing a generalization of the linear Sachs-Wolfe effect at any order in perturbation theory. We show how to compute the n-point connected correlation functions of the large-scale CMB anisotropies for generic primordial seeds provided by standard slow-roll inflation as well as the curvaton and other scenarios for the generation of cosmological perturbations. As an application of our formalism, we compute the three- and four-point connected correlation functions whose detection in future CMB experiments might be used to assess the level of primordial non-Gaussianity, giving the theoretical predictions for the parameters of quadratic and cubic non-linearities f_NL and g_NL.

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N. Bartolo, S. Matarrese, A. Riotto. 2005-08-31. Non-Gaussianity of Large-Scale Cosmic Microwave Background Anisotropies beyond Perturbation Theory. https://doi.org/10.1088/1475-7516%2F2005%2F08%2F010

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