Non-Gaussianity Analysis on WMAP Data

[jal]

Found the following. I leave the comment to the experts.

http://infoscience.epfl.ch/record/108833/files/
Y. Wiaux, P. Vielva, R.B. Barreiro, E. MartÃnez-González and P. Vandergheynst, Non-Gaussianity analysis on local morphological measures of WMAP data, Mon. Not. R. Astron. Soc., Vol. 385, pp. 939, 2008.

“The observed non-Gaussianity is therefore probably to be imputed to the CMB temperature field itself, thereby questioning the basic inflationary scenario upon which the concordance cosmological model relies”
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Probing dark energy with steerable wavelets through correlation of WMAP and NVSS local morphological measures
Mcewenetal-MNRAS384-1289-2008

 

[marcus]

If anyone is interested in this rather specialized topic (WMAP observation of CMB non-Gaussianity) I would suggest they check out this more recent paper, which contains a REVIEW along with an interesting result.

http://arxiv.org/abs/0803.2157
A high-significance detection of non-Gaussianity in the WMAP 5-year data using directional spherical wavelets
Authors: J. D. McEwen, M. P. Hobson, A. N. Lasenby, D. J. Mortlock
(Submitted on 14 Mar 2008 (v1), last revised 29 Apr 2008 (this version, v2))

Abstract: We repeat the directional spherical real Morlet wavelet analysis, used to detect non-Gaussianity in the Wilkinson Microwave Anisotropy Probe (WMAP) 1-year and 3-year data (McEwen et al. 2005, 2006a), on the WMAP 5-year data. The non-Gaussian signal detected previously is present in the 5-year data at a slightly increased statistical significance of approximately 99%. Localised regions that contribute most strongly to the non-Gaussian signal are found to be very similar to those detected in the previous releases of the WMAP data. When the localised regions detected in the 5-year data are excluded from the analysis the non-Gaussian signal is eliminated.
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It seems that dozens of research groups have found non-Gaussian signal in the WMAP data and scores of papers have been published about it.

McEwen et al are at Cambridge and at Blackett Lab---they seem very much on top of this subject and they provide a map (Figure 4) with a few isolated dots on it where the non-Gaussianity is localized.
If one assumes that these few dots are unexplained sources of the non-Gaussian component and eliminates them, then the non-Gaussianity goes away. According to them.

As I am not an expert in this, I'd toss this out as a question in case anyone is interested. It's not of earthquake importance but could it be that the overall random mottling of the CMB temperature map is essentially perfect but has a few little blemishes caused by actual microwave sources----or otherwise explainable?
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BTW it now seems that the big "Void" people were talking about some 6 months ago is possibly merely an artifact of the data analysis and not really there.
The report came out recently. Don't know if anyone has posted on it yet.

 

[Chronos]

A question: If unknown contamination effects are present in the WMAP data, what is the probability they would result in non-gaussian artifacts?