Constraining Primordial Gravitational Waves Using Present and Future CMB Polarization Experiments

Nov 26, 2018 - 11:00 am to 12:00 pm

Campus, Varian 355

Victor Buza (Harvard-Smithsonian Center for Astrophysics)

Finding direct evidence of Primordial Gravitational Waves (PGWs) is one of the most exciting and important goals in fundamental physics today. The polarized light of the Cosmic Microwave Background (CMB) provides a powerful dataset from which we may detect PGWs and draw quantitative conclusions about the early Universe. The problem is challenging not least because the CMB polarization is orders of magnitude fainter than the complex contaminating foregrounds in our galaxy. In this talk I will describe an optimal multi-component spectral-based likelihood analysis framework for joint analyses of CMB polarization datasets designed to decouple contributions from any PGW signal from galactic foregrounds, and its subsequent use for the recently published analysis of Planck, WMAP and new BICEP/Keck data to derive the tightest current constraints on PGWs.


I will also talk about modifying this likelihood pipeline into a spectral-based Fisher projection framework that directly uses information from current BICEP/Keck achieved performances to robustly forecast the science reach of upcoming CMB-polarization endeavors. This framework is different from others of this kind through its direct implementation of real-life experimental inefficiencies and offers a flexible and rapid way to forecast and optimize the design of future experiments. I will present its application in the context of the BICEP Array and CMB-S4 design processes, yielding the results presented in the CMB-S4 Science Book and establishing the current baseline BICEP Array and CMB-S4 experiments.