Fredagskollokvium: Yabebal Fantaye: Test of the Cosmological principles in the Planck era

The cosmological principles states that on a sufficiently large scales, the Universe is isotropic, no preferred directions, and homogeneous, no preferred places. Using the first year WMAP data Eriksen et. al. 2004 and Hansen et. al. 2004 have shown that the power in the CMB data is not symmetric in the sky, suggesting the breakdown of the isotropic assumption in the Cosmological principle. This claim, which was based on only the large scales, has been confirmed to continue in the small scales, up to multipoles of 600, by Hansen et. al. 2009 and Axelsson et. al. 2013 using the WMAP 5-year and 9-year data. In addition, the Planck data with different systematics and foreground cleaning methods has confirmed the same power asymmetry. In this talk I will briefly summarise the history of power asymmetry in the CMB data and present the current status from the latest WMAP and Planck data.