Improved constraints on primordial gravitational waves using BICEP/Keck observations*

In this talk, I will present the latest analysis from the BICEP/Keck experiments. This result shows the tensor-to-scalar ratio r < 0.036 at 95% confidence with σ(r)=0.009, which is the tightest constraint to date on primordial gravitational waves.

Cosmic inflation was postulated to solve the horizon, flatness and monopole problems arise from the standard LCDM model. Inflation generically predicts the existence of primordial gravitational waves which would leave a unique degree-scale B-mode polarization pattern in the cosmic microwave background (CMB). If detected, this can serve as a probe to the early Universe and high energy physics inaccessible with existing particle accelerators. The BICEP/Keck experiments are a series of telescopes at the South Pole designed to search for this degree-scale B-mode signature in the CMB. Our latest release (BK18) includes new data collected through the 2018 season, and is the first to utilize observations from the 95GHz BICEP3 telescope.