Testing inflation with new CMB polarization measurements

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This project addresses the question, 'Did cosmic inflation happen in the early Universe?' If so it would have produced a gravitational wave background, imprinted on the polarization of the Cosmic Microwave Background. In the past year a tantalizing polarized signal was seen by the BICEP2 experiment, but only at a single wavelength, and was then found to be most likely due to contaminating emission from our own Milky Way. To make progress, in Oxford we are part of the Atacama Cosmology Telescope collaboration, with ACTPol currently observing the CMB in Chile. AdvACT will be the third generation receiver in operation 2016-18; it will map half the sky in polarization at multiple wavelengths, and will be able to look for smaller inflationary signals than yet reached.This project will have some emphasis on the theoretical interpretation of the possible B-mode polarization signal, and on analysis techniques including the modeling and separation of polarized Galactic foregrounds. The work will also include simulations and preparations for next generation instruments, including the ground-based 'CMB-S4' project, and the LiteBIRD satellite. A core part of the PhD is anticipated to be spent working with Japanese colleagues on LiteBIRD science.