Temperature and polarization patterns in anisotropic cosmologies

• Main Author: Sung, Rockhee
• Published: Cardiff University 2010
• Subjects: 523.1
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.584949

We study the coherent temperature and polarization patterns produced in homogeneous but anisotropic cosmological models. We show a range of results for all Bianchi types with a Friedman-Robertson-Walker limit (i.e. Types I, V, VIIo, VII and IX) to illustrate the possible behaviours that can obtained. We show that localized features in the temperature pattern, perhaps similar to the cold spot observed in the Wilkinson Microwave Anisotropy Probe (WMAP) data, can be generated in models with negative spatial curvature, i.e. Bianchi types V and VII. In Bianchi VII/j, however, rotation of the polarization angle as light propagates along geodesies can convert E modes into B modes but in Bianchi V this does not happen. We also discuss general properties of the radiation fields. We then consider two possible ways to characterize patterns in CMB temperature maps generated by these anisotropic Bianchi cosmological models. The Pixel Distribution Histogram (PDH) is used as the basis of a discussion of what we mean by 'Gaussianity'. The other method uses multipole vectors, which are de rived from the perspective of polynomial defined on the 2-sphere. Although the PDH study gives us limited information to characterize the statistical properties of Bianchi universes, the method using multipole vectors demonstrates a very strong correlation between the multipoles and suggests this could be useful for diagnosing the presence of global asymmetry in the cosmic microwave background.