Non-Gaussianity of the Derived Maps from the First-Year Wilkinson Microwave Anisotropy Probe Data

We present non-Gaussianity testing on derived maps from the recently released first-year Wilkinson Microwave Anisotropy Probe data by Tegmark, de Oliveria-Costa, & Hamilton. Our test is based on a phase-mapping technique that has the advantage of testing non-Gaussianity at separate multipole bands. We show that their foreground-cleaned map is against the random-phase hypothesis at all four multipole bands centered around ℓ = 150, 290, 400, and 500. Their Wiener-filtered map, on the other hand, is Gaussian for ℓ < 250 and marginally Gaussian for 224 < ℓ < 350. However, we see the evidence of non-Gaussianity for ℓ > 350 as we detect certain degrees of phase coupling, hence against the random-phase hypothesis. Our phase-mapping technique is particularly useful for testing the accuracy of component separation methods.