Evolution of second - order cosmological perturbations and non-Gaussianity
Sep, 2003
14 pages
Published in:
- JCAP 01 (2004) 003
e-Print:
- astro-ph/0309692 [astro-ph]
Report number:
- DFPD-A-03-36
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Abstract: (arXiv)
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.- space-time: Robertson-Walker
- space-time: perturbation
- fluid
- inflation
- curvaton
- temperature: anisotropy
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