Morphological Studies of the CMB: Non-standard Models and Foregrounds

Jaffe, Theresa (2006): Morphological Studies of the CMB: Non-standard Models and Foregrounds. Dissertation, LMU München: Faculty of Physics

Abstract

Recent measurements of the Cosmic Microwave Background (CMB) have allowed the most accurate determinations yet of the parameters of the standard CDM model, but the data also contain intriguing anomalies that are inconsistent with the assumptions of statistical isotropy and Gaussianity. This work investigates possible sources of such anomalies by studying the morphology of the CMB. An unexpected correlation is found between the CMB anisotropies and a temperature pattern generated in a Bianchi Type VIIh universe, i.e., an anisotropic universe allowing a universal rotation or vorticity. This model is found to be incompatible with other observations of the cosmological parameters, but correcting for such a component can serendipitously remove many of the anomalies from the WMAP sky. This result indicates that an alternative cosmological model producing such a morphology may be needed. A similar cross-correlation method applied to the microwave foregrounds studies the variation of the spectral behaviours of the Galactic emission processes across the sky. The results shed light on the unexpectedly low free-free emission amplitude as well as the nature of the anomalous dust-correlated emission that dominates at low frequencies. As a complementary method, phase statistics apply to situations where no a priori knowledge of 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 analysis shows that these may prove powerful tools in the study of non-Gaussianity and anisotropy.

• Item Type: Theses (Dissertation, LMU Munich)
• Keywords: cosmology, cosmic microwave background
• Subjects: 500 Natural sciences and mathematics > 530 Physics; 500 Natural sciences and mathematics
• Faculties: Faculty of Physics
• Language: English
• Date of oral examination: 9. October 2006
• 1. Referee: White, Simon D. M.
• Signature of the printed copy: 0001/UMC 15716