An Estimate of the Primordial Non-Gaussianity Parameter f_NL Using the Needlet Bispectrum from WMAP

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 l_max=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.

9 pages, 2 figures

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• Unveiling the Dynamics of the Universe
• Improved constraints on primordial non-Gaussianity for the Wilkinson Microwave Anisotropy Probe 5-yr data
• Examining the consistency relations describing the three-point functions involving tensors
• On the linear term correction for needlets/wavelets non-Gaussianity estimators
• A Simple Proposal for Radial 3D Needlets
• The scalar bi-spectrum during preheating in single field inflationary models
• How the curvaton scenario, modulated reheating and an inhomogeneous end of inflation are related
• Impact of the 1/f noise and the asymmetric beam on non-Gaussianity searches with Planck
• Testing for foreground residuals in the Planck foreground cleaned maps: A new method for designing confidence masks
• Integrated Markov Chain Monte Carlo (MCMC) analysis of primordial non-Gaussianity (f_NL) in the recent CMB data