Journal Article

Constraints on primordial non–Gaussianity from a needlet analysis of the <i>WMAP</i>–5 data

Davide Pietrobon, Paolo Cabella, Amedeo Balbi, Giancarlo De Gasperis and Nicola Vittorio

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 396, issue 3, pages 1682-1688
Published in print July 2009 | ISSN: 0035-8711
Published online June 2009 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2009.14847.x
Constraints on primordial non–Gaussianity from a needlet analysis of the WMAP–5 data

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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 fNL. We apply a third–order estimator of the needlet coefficients skewness and compute the χ2 statistics of its distribution. We obtain −80 < fNL < 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 fNL 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 fNL improve to −50 < fNL < 110 at 95 per cent confidence level.

Keywords: methods: data analysis; cosmic microwave background; early Universe

Journal Article.  4618 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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