Open AccessCubic anomalies in the Wilkinson Microwave Anisotropy Probe
Author(s) -
Land Kate,
Magueijo João
Publication year - 2005
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.08707.x
Subject(s) - bispectrum , physics , asymmetry , cosmic microwave background , anisotropy , spectral density , confidence interval , consistency (knowledge bases) , range (aeronautics) , quadrupole , non gaussianity , astrophysics , statistics , optics , particle physics , quantum mechanics , mathematics , geometry , materials science , composite material
We perform a frequentist analysis of the bispectrum of the Wilkinson Microwave Anisotropy Probe first‐year data. We find clear signal domination up to ℓ≈ 200 , with overall consistency with Gaussianity, except for the following features. There is a flat patch (i.e. a low χ 2 region) in the same‐ℓ components of the bispectrum spanning the range ℓ= 32–62 ; this may be interpreted as ruling out Gaussianity at the 99.6 per cent confidence level. There is also an asymmetry between the north and south inter‐ℓ bispectrum components at the 99 per cent confidence level. The preferred asymmetry axis correlates well with the (ℓ, b ) = (57, 10) direction quoted in the literature for asymmetries in the power spectrum and three‐point correlation function. However, our analysis of the quadrupole (its bispectrum and principal axes) fails to make contact with previously claimed anomalies.