Bartolo N, Matarrese S, Riotto A. Gauge-invariant temperature anisotropies and primordial non-Gaussianity.
PHYSICAL REVIEW LETTERS 2004;
93:231301. [PMID:
15601141 DOI:
10.1103/physrevlett.93.231301]
[Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2004] [Indexed: 05/24/2023]
Abstract
We provide the gauge-invariant expression for large-scale cosmic microwave background temperature fluctuations at second-order perturbation theory. This enables us to define unambiguously the nonlinearity parameter f(NL), which is used by experimental collaborations to pin down the level of non-Gaussianity in the temperature fluctuations. Furthermore, it contains a primordial term encoding all the information about the non-Gaussianity generated at primordial epochs and about the mechanism which gave rise to cosmological perturbations, thus neatly disentangling the primordial contribution to non-Gaussianity from the one caused by the postinflationary evolution.
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