Open AccessA high‐significance detection of non‐Gaussianity in the WMAP 3‐yr data using directional spherical wavelets
Author(s) -
McEwen J. D.,
Hobson M. P.,
Lasenby A. N.,
Mortlock D. J.
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society: letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.067
H-Index - 122
eISSN - 1745-3933
pISSN - 1745-3925
DOI - 10.1111/j.1745-3933.2006.00206.x
Subject(s) - cmb cold spot , non gaussianity , cosmic microwave background , wavelet , morlet wavelet , astrophysics , physics , gaussian , statistic , anisotropy , wavelet transform , statistics , mathematics , computer science , artificial intelligence , optics , discrete wavelet transform , quantum mechanics
We repeat the directional spherical real Morlet wavelet analysis, used to detect non‐Gaussianity in the Wilkinson Microwave Anisotropy Probe ( WMAP ) 1‐yr data, on the WMAP 3‐yr data. The non‐Gaussian signal previously detected is indeed present in the 3‐yr data, although the significance of the detection is reduced. Using our most conservative method for constructing significance measures, we find that the significance of the detection of non‐Gaussianity drops from 98.3 ± 0.4 to 94.9 ± 0.7 per cent; the significance drops from 99.3 ± 0.3 to 97.2 ± 0.5 per cent using a method based on the χ 2 statistic. The wavelet analysis allows us to localize most likely sources of non‐Gaussianity on the sky. We detect very similar localized regions in the WMAP 1‐yr and 3‐yr data, although the regions extracted appear more pronounced in the 3‐yr data. When all localized regions are excluded from the analysis, the 3‐yr data are consistent with Gaussianity.