Journal Article

Bounds on non-Gaussianity in the variance from small-scale cosmic microwave background observations

E. Gaztañaga, P. Fosalba and E. Elizalde

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 295, issue 2, pages L35-L39
Published in print April 1998 | ISSN: 0035-8711
Published online April 1998 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1046/j.1365-8711.1998.01439.x
Bounds on non-Gaussianity in the variance from small-scale cosmic microwave background observations

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Abstract

We compare the latest results from CMB experiments at scales around le ∼ 150 over different parts of the sky to test the hypothesis that they are drawn from a Gaussian distribution, as is usually assumed. Using both the diagonal and the full covariance χ2 tests, we compare the data with different sets of strategies and find in all cases incompatibility with the Gaussian hypothesis above the 1σ level. We show how to include a generic non-Gaussian signal in the data analysis. Results from CMB observations can be made compatible with each other by assuming a non-Gaussian distribution for the signal, with a kurtosis at a level B4 = 〈δ4Tc/〈δ2T2 ≃ 90. A possible interpretation of this result is that the initial fluctuations at the surface of last scattering are strongly non-Gaussian. Another interpretation is that the systematic errors have been underestimated in all experiments by a factor of 2. Other explanations include foreground contamination, non-linear effects or a combination of these.

Keywords: cosmic microwave background; large-scale structure of Universe

Journal Article.  0 words. 

Subjects: Astronomy and Astrophysics

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