Morphological Studies of the CMB: Non-standard Models and Foregrounds
Recent measurements of the Cosmic Microwave Background (CMB) have allowed the most\naccurate determinations yet of the parameters of the standard CDM model, but the data\nalso contain intriguing anomalies that are inconsistent with the assumptions of statistical\nisotropy and Gaussianity. This work investigates possible sources of such anomalies by\nstudying the morphology of the CMB. An unexpected correlation is found between the\nCMB anisotropies and a temperature pattern generated in a Bianchi Type VIIh universe,\ni.e., an anisotropic universe allowing a universal rotation or vorticity. This model is found to\nbe incompatible with other observations of the cosmological parameters, but correcting for\nsuch a component can serendipitously remove many of the anomalies from the WMAP sky.\nThis result indicates that an alternative cosmological model producing such a morphology\nmay be needed. A similar cross-correlation method applied to the microwave foregrounds\nstudies the variation of the spectral behaviours of the Galactic emission processes across the\nsky. The results shed light on the unexpectedly low free-free emission amplitude as well as\nthe nature of the anomalous dust-correlated emission that dominates at low frequencies. As\na complementary method, phase statistics apply to situations where no a priori knowledge\nof the spatial structure informs the search for a non-Gaussian signal. Such statistics are applied to compact topological models as well as to foreground residuals, and a preliminary\nanalysis shows that these may prove powerful tools in the study of non-Gaussianity and\nanisotropy.