Measurements of Cosmic Microwave Background B-mode polarization allow us to search for primordial gravitational waves, which are predicted by theories of cosmic inflation. The BICEP/Keck series of small aperture polarimeters have been operating since 2010 from Amundsen-Scott South Pole Station and have produced leading constraints on inflation. I will discuss the most recent results from BICEP3 and Keck Array, which set an upper limit on the tensor-to-scalar ratio, r < 0.036 at 95% confidence. Future limits on r will increasingly depend on our ability to separate primordial B modes from those sourced by foregrounds or gravitational lensing. I will also provide an update on the status and future plans for BICEP Array, our next-generation multi-frequency instrument, and collaboration with SPT-3G.
https://go.illinois.edu/AstroColloquium