Deviation from Gaussianity in the cosmic microwave background temperature fluctuationsArmando Bernui1, Constantino Tsallis2 and Thyrso Villela1
1 Instituto Nacional de Pesquisas Espaciais, Divisão de Astrofísica - Av. dos Astronautas 1758, 12227-010 São José dos Campos, SP, Brazil
2 Centro Brasileiro de Pesquisas Físicas - Rua Xavier Sigaud 150, 22290-180 Rio de Janeiro, RJ, Brazil
received 6 October 2006; accepted in final form 19 February 2007; published April 2007
published online 19 March 2007
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 of these data can be quite well fitted by the anomalous probability distribution emerging within nonextensive statistical mechanics, based on the entropy ( ). For the CMB frequencies analysed, 40.7, 60.8, and 93.5 GHz, is well described by , with , 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, to fit the three-year data.
98.80.Es - Observational cosmology (including Hubble constant, distance scale, cosmological constant, early Universe, etc.).
98.70.Vc - Background radiations.
05.90.+m - Other topics in statistical physics, thermodynamics, and nonlinear dynamical systems.
© Europhysics Letters Association 2007