Multiple Methods for Estimating the Bispectrum of the Cosmic Microwave Background with Application to the MAXIMA Data

M. G. Santos; A. Heavens; A. Balbi; J. Borrill; P. G. Ferreira; S. Hanany; A. H. Jaffe; A. T. Lee; B. Rabii; P. L. Richards; G. F. Smoot; R. Stompor; C. D. Winant; J. H. P. Wu

doi:10.1046/j.1365-8711.2003.06438.x

paper

Multiple Methods for Estimating the Bispectrum of the Cosmic Microwave Background with Application to the MAXIMA Data

arXiv:astro-ph/0211123 · doi:10.1046/j.1365-8711.2003.06438.x

Abstract

We describe different methods for estimating the bispectrum of Cosmic Microwave Background data. In particular we construct a minimum variance estimator for the flat-sky limit and compare results with previously-studied frequentist methods. Application to the MAXIMA dataset shows consistency with primordial Gaussianity. Weak quadratic non-Gaussianity is characterised by a tunable parameter $f_{N L}$ , corresponding to non-Gaussianity at a level $\sim 1 0^{- 5} f_{N L}$ (ratio of non-Gaussian to Gaussian terms), and we find limits of $∣ f_{N L} ∣ < 950$ for the minimum-variance estimator and $∣ f_{N L} ∣ < 1650$ for the usual frequentist estimator. These are the tightest limits on primordial non-Gaussianity which include the full effects of the radiation transfer function.

24 pages, 13 figures