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Multiple methods for estimating the bispectrum of the cosmic microwave background with application to the MAXIMA data
Ist Teil von
Monthly notices of the Royal Astronomical Society, 2003-05, Vol.341 (2), p.623-643
Ort / Verlag
Oxford, UK: Blackwell Science Ltd
Erscheinungsjahr
2003
Quelle
Wiley Online Library Journals Frontfile Complete
Beschreibungen/Notizen
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 data set shows consistency with primordial Gaussianity. Weak quadratic non-Gaussianity is characterized by a tunable parameter fNL, corresponding to non-Gaussianity at a level of ∼10−5fNL (the ratio of non-Gaussian to Gaussian terms), and we find limits of fNL= 1500 ± 950 for the minimum-variance estimator and fNL= 2700 ± 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.