Colloq Abstract - Barron
October 5, 2018
11:00am Mountain
Darcy Barron (UNM)
Cosmology and fundamental physics with cosmic microwave background polarization measurements
Abstract
The cosmic microwave background (CMB) field has a fifty-year history of measurements and discoveries from an evolving series of experiments, transforming our understanding and refining our models of the Universe. The past several years have been very exciting for the CMB field, with multiple experiments finally reaching the level of sensitivity and systematics control to detect the B-mode polarization signal from gravitational lensing. This faint pattern is a powerful probe to study the composition and large-scale structure of the universe. A unique B-mode polarization pattern would also be imprinted by inflationary gravitational in the early universe. Measuring this signal would provide direct evidence for inflation, as well as provide insight into the mechanism and energy scale of inflation.
I will discuss my work on POLARBEAR, a dedicated CMB polarization experiment located in the Atacama desert in Chile, designed to map the gravitational lensing signal as well as do a deep search for the inflationary signal. POLARBEAR-1 started observations in 2012, and after just one year of observations reached a map depth that enabled detection of B-mode polarization. Since POLARBEAR-1 began observations, we have been developing a powerful new instrument, POLARBEAR-2, and we have expanded our site to include 2 new telescopes, known as the Simons Array. With high sensitivity and large sky coverage, POLARBEAR-2/Simons Array will create a detailed survey of B-mode polarization, with spectral information used to isolate the CMB signal from astrophysical foregrounds. Fully extracting new cosmology and fundamental physics from CMB B-mode polarization requires an increase in sensitivity of two order of magnitudes beyond what has currently been deployed, and the CMB community has begun the coordination to design and deploy this ambitious project, known as CMB-S4.
