Pure-B Filtering by Messenger Method

Abstract

By Michael Ray, Physics and Mathematics

Advisor: Colin Bischoff

Abstract: The polarization of the Cosmic Microwave Background (CMB) is a unique probe for studying primordial gravitational waves created at time of the big bang. Gravitational waves show up as B modes in a polarization map but there are ambiguous B modes on a partial sky map around the boundary of the sky cut. To decide which B modes to throw out and which to keep, we employ the "messenger method" - an iterative method to solve for a filtered map. The effectiveness of this method has been demonstrated on simulations of the upcoming CMB-S4 experiment.