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Evolution of Second-Order Cosmological Perturbations and Non-Gaussianity

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

We present a second-order gauge-invariant formalism to study the evolution of curvature perturbations in a Friedmann-Robertson-Walker universe filled by multiple interacting fluids. We apply such a general formalism to describe the evolution of the second-order curvature perturbations in the standard one-single field inflation, in the curvaton and in the inhomogeneous reheating scenarios for the generation of the cosmological perturbations. Moreover, we provide the exact expression for the second-order temperature anisotropies on large scales, including second-order gravitational effects and extend the well-known formula for the Sachs-Wolfe effect at linear order. Our findings clarify what is the exact non-linearity parameter f_NL entering in the determination of higher-order statistics such as the bispectrum of Cosmic Microwave Background temperature anisotropies. Finally, we compute the level of non-Gaussianity in each scenario for the creation of cosmological perturbations.

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N. Bartolo, S. Matarrese, A. Riotto. 2003-10-06. Evolution of Second-Order Cosmological Perturbations and Non-Gaussianity. https://doi.org/10.1088/1475-7516%2F2004%2F01%2F003

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