Constraints on primordial non-Gaussianity from a needlet analysis of the WMAP-5 data |
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| Authors: | Davide Pietrobon Paolo Cabella Amedeo Balbi Giancarlo de Gasperis Nicola Vittorio |
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| Institution: | Dipartimento di Fisica, Universitàdi Roma 'Tor Vergata', via della Ricerca Scientifica 1, 00133 Roma, Italy;Institute of Cosmology and Gravitation, University of Portsmouth, Mercantile House, Portsmouth PO1 2EG;Dipartimento di Fisica, UniversitàLa Sapienza, P. le A. Moro 2, 00185 Roma, Italy;INFN Sezione di Roma 'Tor Vergata', via della Ricerca Scientifica 1, 00133 Roma, Italy |
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| Abstract: | We look for a non-Gaussian signal in the Wilkinson Microwave Anisotropy Probe ( WMAP ) 5-year temperature anisotropy maps by performing a needlet-based data analysis. We use the foreground-reduced maps obtained by the WMAP team through the optimal combination of the W, V and Q channels, and perform realistic non-Gaussian simulations in order to constrain the non-linear coupling parameter f NL. We apply a third-order estimator of the needlet coefficients skewness and compute the χ2 statistics of its distribution. We obtain ?80 < f NL < 120 at 95 per cent confidence level, which is consistent with a Gaussian distribution and comparable to previous constraints on the non-linear coupling. We then develop an estimator of f NL based on the same simulations and we find consistent constraints on primordial non-Gaussianity. We finally compute the three-point correlation function in needlet space: the constraints on f NL improve to ?50 < f NL < 110 at 95 per cent confidence level. |
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| Keywords: | methods: data analysis cosmic microwave background early Universe |
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