Colloquium on Dec. 1, 2022

The search for primordial gravitational waves with CMB experiments in the Atacama desert and space

Speaker: Yuji Chinone (KEK)

Venue: Video Conference

Time: 16:00 PM, Thursday, Dec. 1, 2022

Abstract:

Searching for primordial gravitational waves (PGWs) is one of the key topics in cosmology because it must be smoking gun evidence for the origin of the universe. PGWs leave a characteristic pattern on the cosmic microwave background (CMB) in the form of "B-mode" polarization. In March 2014, POLARBEAR in the Atacama desert reported a measurement of B-modes at sub-degree scales created by gravitational lensing effects; BICEP2 on the South Pole claimed to detect primordial B-modes at degree scales, but it has been confirmed that the signal is emitted from dust in our galaxy. Until now, no experiment has detected primordial B-modes yet, so we are actively observing CMB polarization and developing/building future experiments. In this talk, I will briefly explain the motivation of B-mode measurements first, then summarize the status of the measurements and POLARBEAR's achievements. Next I will show the progress of the current experiments, e.g. the Simons Array experiment. Then I'll talk about next-generation ground-based CMB experiments. At the end of my talk, I will mention their synergies with a satellite mission, i.e. LiteBIRD.

Report PPT:  SWIFAR_Yuji Chinone.pdf