We use the full bispectrum of spherical needlets applied to the WMAP data of the cosmic microwave background as an estimator for the primordial non-Gaussianity parameter f NL. We use needlet scales up to ellmax = 1000 and the KQ75 galactic cut and find f NL = 84 ± 40 corrected for point-source bias. We also introduce a set of consistency tests to validate our results against the possible influence of foreground residuals or systematic errors. In particular, fluctuations in the value of f NL obtained from different frequency channels, different masks, and different multipoles are tested against simulated maps. All variations in f NL estimates are found statistically consistent with simulations.
An Estimate of the Primordial Non-Gaussianity Parameter f_NL using the Needlet Bispectrum from WMAP
LIGUORI, MICHELE;MATARRESE, SABINO
2009
Abstract
We use the full bispectrum of spherical needlets applied to the WMAP data of the cosmic microwave background as an estimator for the primordial non-Gaussianity parameter f NL. We use needlet scales up to ellmax = 1000 and the KQ75 galactic cut and find f NL = 84 ± 40 corrected for point-source bias. We also introduce a set of consistency tests to validate our results against the possible influence of foreground residuals or systematic errors. In particular, fluctuations in the value of f NL obtained from different frequency channels, different masks, and different multipoles are tested against simulated maps. All variations in f NL estimates are found statistically consistent with simulations.
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