Small-scale secondary anisotropies in the Cosmic Microwave Background.

摘要

One of the main harbingers of the modern age of precision cosmology, the Cosmic Microwave Background (CMB) has proven itself to be a veritable trove of cosmological information. With the aid of experiments such as the WMAP satellite, precision measurements of the CMB anisotropy spectra are now being made.;The next small-scale phenomenon to be explored is the small-scale CMB polarization anisotropies generated by Thomson scattering of the local photon quadrupole anisotropy during reionization. The underlying physics behind this effect are studied along with the observational information it potentially contains. Observational data of the remote quadrupole is capable of improving constraints in the CMB temperature anisotropy spectrum on scales of ℓ ∼ 11 as well as offering information concerning the reconstruction of the primordial density perturbations on gigaparsec scales in our local universe.;This work will first explore the physics of the Vishniac effect, a small-scale CMB temperature anisotropy created by the Compton scattering of CMB photons by free electrons caught in a line-of-sight bulk flow. The Vishniac effect arises due to a density enhancement in the electrons caused by gravitational potentials in both the linear and nonlinear regimes and contributes significant power to the CMB temperature anisotropy power spectrum on small scales. This effect is strongly dependent upon cosmology and as such this dependence is investigated for all experimentally-allowed values of the fundamental cosmological parameters. This analysis is performed for both the linear Vishniac effect as well as its nonlinear extension. Following this analysis a fitting function, capable of predicting the power generated by the Vishniac effect over a range of scales for any allowed cosmology, is investigated. This function proves to be an accurate and efficient way of computing the Vishniac effect for any input cosmology.