Testing the isotropy of the Cosmic Microwave Backround

Abstract

There have recently been several claims of an asymmetric distribution of large scale fluctuations in the WMAP data. I review some recent results from a test of isotropy of the power spectrum at all scales and show how the power is asymmetrically distributed for the multipole range l=5-40 in three WMAP frequency channels. I compare this to a recent detection of a non-Gaussian signal in one part of the sky using the local curvature properties of the cosmic microwave background fluctuation field. I find that there may be a common origin of these two findings due to a similar direction and frequency independence of the results.