On the linear term correction for needlets/wavelets non-Gaussianity estimators

TL;DR

This paper derives a linear correction for needlet and wavelet bispectrum estimators, improving non-Gaussianity measurements in CMB data and applying it to WMAP data to refine the fNL estimate.

Contribution

It introduces a linear correction term for needlet and wavelet estimators, enhancing their accuracy in non-Gaussianity analysis of CMB data.

Findings

Error bars improved by 10-20% on masked WMAP-like data.

Correction term vanishes for full-sky isotropic noise.

Estimated fNL from WMAP 7-year data is 37.5 ± 21.8.

Abstract

We derive the linear correction term for needlet and wavelet estimators of the bispectrum and the non-linearity parameter fNL on cosmic microwave background radiation data. We show that on masked WMAP-like data with anisotropic noise, the error bars improve by 10-20% and almost reach the optimal error bars obtained with the KSW estimator (Komatsu et al 2005). In the limit of full-sky and isotropic noise, this term vanishes. We apply needlet and wavelet estimators to the WMAP 7-year data and obtain our best estimate fNL=37.5 \pm 21.8.