WMAP 5-year constraints on fnl with wavelets

Abstract

We present a Gaussianity analysis of the WMAP 5-year Cosmic Microwave Background (CMB) temperature anisotropy data maps. We use several third order estimators based on the spherical Mexican hat wavelet. We impose constraints on the local non-linear coupling parameter fnl using well motivated non-Gaussian simulations. We analyse the WMAP maps at resolution of 6.9 arcmin for the Q, V, and W frequency bands. We use the KQ75 mask recommended by the WMAP team which masks out 28% of the sky. The wavelet coefficients are evaluated at 10 different scales from 6.9 to 150 arcmin. With these coefficients we compute the third order estimators which are used to perform a chi-squared analysis. The chi-squared statistic is used to test the Gaussianity of the WMAP data as well as to constrain the fnl parameter. Our results indicate that the WMAP data are compatible with the Gaussian simulations, and the fnl parameter is constrained to -8 < fnl < +111 at 95% CL for the combined V+W map. This value has been corrected for the presence of undetected point sources, which add a positive contribution of Delta_fnl = 3+-5 in the V+W map. Our results are very similar to those obtained by Komatsu et al (2008) using the bispectrum.

10 pages, 5 figures, 2 tables. Minor revision, references added, accepted for publication in MNRAS

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• Analytic Minkowski Functionals of the Cosmic Microwave Background: Second-order Non-Gaussianity with Bispectrum and Trispectrum
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• Constraints on Primordial Non-Gaussianity from a Needlet Analysis of the WMAP-5 Data
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• Foreground influence on primordial non-Gaussianity estimates: needlet analysis of WMAP 5-year data
• On the optimality of the spherical Mexican hat wavelet estimator for the primordial non-Gaussianity
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• Wilkinson Microwave Anisotropy Probe 7-yr constraints on fNL with a fast wavelet estimator
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• Statistics of the excursion sets in models with local primordial non-Gaussianity
• Constraints on fNL from Wilkinson Microwave Anisotropy Probe 7-year data using a neural network classifier
• An overview of the current status of CMB observations
• Investigating non-Gaussianity in Cosmic Microwave Background Temperature Maps using Spherical Harmonic Phases
• Integrated Markov Chain Monte Carlo (MCMC) analysis of primordial non-Gaussianity (f_NL) in the recent CMB data