Large-Angular Correlations in the Cosmic Microwave Background

by Mr Yin-Zhe Ma (Institute of Astronomy, University of Cambridge)

Thursday 1 Apr 2010, 16:00 → 17:15 Europe/Brussels

E/3rd floor-E.349 - Seminar room (E.349) (Marc de Hemptinne (chemin du Cyclotron, 2, Louvain-la-Neuve))

The simple six-parameter LCDM model provides a successful fit to the WMAP data. However, it was a long standing argument that the lack of large angular correlations of the CMB temperature field provides strong evidence against the standard, statistically isotropic, LCDM cosmology. In this talk, I will compare various estimators of the temperature correlation function showing how they depend on assumptions of statistical isotropy and how they perform on the WMAP 5 year ILC maps with and without a sky cut. I will also show that the low multipole harmonics that determine the large-scale features of the temperature correlation function can be reconstructed accurately, independent of any assumptions concerning statistical isotropy, from the data that lie outside the sky cuts. The temperature correlation functions computed from our reconstructions are in good agreement with those computed from the whole sky. A Bayesian analysis of the large-scale correlations is presented which shows that the data cannot exclude the standard LCDM model.