(Centre d’Etude Spatiale des Rayonnements, Toulouse)
Jeudi 22 Octobre 2009 à 11h
Is the Universe Isotropic ? evidence from WMAP
Two of the most fundamental principles guiding cosmologists are the principles of cosmological homogeneity (the Copernican Principle - that any measurable property of the Universe is the same from all locations) and of cosmological isotropy (that the Universe looks the same in all directions). Measurements of the Cosmic Microwave Background (CMB) by NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) are generally held to provide definitive evidence in support of such a Universe, seeded by fluctuations generated in an inflationary era. Here, I describe recent results that the CMB contains anomalous structure on large angular scales, suggesting the presence of a preferred direction to the Universe. This yields a possible indication that the principle of isotropy may need to be abandoned.