Wilkinson Microwave Anisotropy Probe 7-yr constraints on fNL with a fast wavelet estimator

Abstract

A new method to constrain the local non-linear coupling parameter fNL based on a fast wavelet decomposition is presented. Using a multiresolution wavelet adapted to the HEALPix pixelization, we have developed a method that is 10^2 times faster than previous estimators based on isotropic wavelets and 10^3 faster than the KSW bispectrum estimator, at the resolution of the Wilkinson Microwave Anisotropy Probe (WMAP) data. The method has been applied to the WMAP 7-yr V+W combined map, imposing constraints on fNL of -69 < fNL < 65 at the 95 per cent CL. This result has been obtained after correcting for the contribution of the residual point sources which has been estimated to be fNL = 7 +/- 6. In addition, a Gaussianity analysis of the data has been carried out using the third order moments of the wavelet coefficients, finding consistency with Gaussianity. Although the constrainsts imposed on fNL are less stringent than those found with optimal estimators, we believe that a very fast method, as the one proposed in this work, can be very useful, especially bearing in mind the large amount of data that will be provided by future experiments, such as the Planck satellite. Moreover, the localisation of wavelets allows one to carry out analyses on different regions of the sky. As an application, we have separately analysed the two hemispheres defined by the dipolar modulation proposed by Hoftuft et al. (2009). We do not find any significant asymmetry regarding the estimated value of fNL in those hemispheres.

8 pages, 5 figures. Submitted and Accepted for publication in MNRAS

References in corpus (8)

• Detection of primordial non-Gaussianity (fNL) in the WMAP 3-year data at above 99.5% confidence
• Optimal limits on f_{NL}^{local} from WMAP 5-year data
• Limits on Primordial Non-Gaussianity from Minkowski Functionals of the WMAP Temperature Anisotropies
• A high-significance detection of non-Gaussianity in the WMAP 5-year data using directional spherical wavelets
• An Estimate of the Primordial Non-Gaussianity Parameter f_NL Using the Needlet Bispectrum from WMAP
• Cosmological applications of a wavelet analysis on the sphere
• Particle physics models of inflation
• Improved constraints on primordial non-Gaussianity for the Wilkinson Microwave Anisotropy Probe 5-yr data

Cited by in corpus (11)

• Planck 2013 results. XII. Component separation
• Multi-resolution internal template cleaning: An application to the Wilkinson Microwave Anisotropy Probe 7-yr polarization data
• Local analyses of Planck maps with Minkowski Functionals
• Constraints on general primordial non-Gaussianity using wavelets for the Wilkinson Microwave anisotropy probe 7-year data
• A Simple Proposal for Radial 3D Needlets
• Searching for primordial non-Gaussianity in Planck CMB maps using a combined estimator
• The effect of the linear term on the wavelet estimator of primordial non-Gaussianity
• A weak lensing view on primordial non-Gaussianities
• Exploring local fNL estimators based on the binned bispectrum
• Constraints on fNL from Wilkinson Microwave Anisotropy Probe 7-year data using a neural network classifier
• Integrated Markov Chain Monte Carlo (MCMC) analysis of primordial non-Gaussianity (f_NL) in the recent CMB data