Open AccessThe non‐Gaussian cold spot in Wilkinson Microwave Anisotropy Probe : significance, morphology and foreground contribution
Author(s) -
Cruz M.,
Tucci M.,
MartínezGonzález E.,
Vielva P.
Publication year - 2006
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.1365-2966.2006.10312.x
Subject(s) - cmb cold spot , physics , astrophysics , cosmic microwave background , wavelet , kurtosis , anisotropy , gaussian , cosmic background radiation , optics , statistics , artificial intelligence , mathematics , quantum mechanics , computer science
The non‐Gaussian cold spot in the 1‐yr Wilkinson Microwave Anisotropy Probe ( WMAP ) data, described by Vielva et al. and Cruz et al., is analysed in detail in the present paper. First of all, we perform a more rigorous calculation of the significance of the non‐zero kurtosis detected in WMAP maps by Vielva et al. in wavelet space, mainly generated by the Spot . We confirm the robustness of that detection, since the probability of obtaining this deviation by chance is 0.69 per cent. Afterwards, the morphology of the Spot is studied by applying Spherical Mexican Hat Wavelets with different ellipticities. The shape of the Spot is found to be almost circular. Finally, we discuss if the observed non‐Gaussianity in wavelet space can arise from bad subtracted foreground residues in the WMAP maps. We show that the flat frequency dependence of the Spot cannot be explained by a thermal Sunyaev–Zeldovich effect. Based on our present knowledge of Galactic foreground emissions, we conclude that the significance of our detection is not affected by Galactic residues in the region of the Spot . Considering different Galactic foreground estimates, the probability of finding such a big cold spot in Gaussian simulations is always below 1 per cent.