Deviation from Gaussianity in the cosmic microwave background temperature fluctuations

Recent measurements of the temperature fluctuations of the cosmic microwave background (CMB) radiation from the WMAP satellite provide indication of a non-Gaussian behavior. Although the observed feature is small, it is detectable and analyzable. Indeed, the temperature distribution P-CMB(Delta T) of these data can be quite well. tted by the anomalous probability distribution emerging within nonextensive statistical mechanics, based on the entropy S-q = k{1-f dx [ P( x)](q)}/(q-1) (S-1=-k f dxP(x) In[ P(x)]). For the CMB frequencies analysed, v = 40.7, 60.8, and 93.5GHz, P-CMB(Delta T) is well described by P-q(Delta T) proportional to 1/[1+(q - 1) B(v)(Delta T)(2)](1/(q-1)), with q = 1.04 +/- 0.01, the strongest non- Gaussian contribution coming from the South- East sector of the celestial sphere. Moreover, Monte Carlo simulations exclude, at the 99% confidence level, P-1(Delta T) proportional to e(-B(v)(Delta T)2) to fit the three-year data.