COLLOQUIUM Marta Monelli, IPMU Japan

Half-wave plates in CMB experiments: some pros and cons

Rapidly rotating half-wave plates (HWPs) are becoming a popular choice of polarization modulators in cosmic microwave background (CMB) experiments. They play a crucial role in mitigating 1/f noise and reducing intensity-to-polarization leakage, both of which are beneficial for high-precision polarization measurements. However, HWPs inevitably exhibit non-idealities that can introduce additional systematic effects, potentially impacting the extraction of cosmological parameters. In this talk, I will provide an overview of the key components of a CMB experiment, from data acquisition to analysis, and discuss the advantages of ideal HWPs. I will then explore the impact of HWP non-idealities on critical measurements, such as the tensor-to-scalar ratio and cosmic birefringence angle, highlighting challenges and potential mitigation strategies.

Talk in presence and via Zoom:

https://uni-hamburg.zoom.us/j/66006535328?pwd=aGkrSjJIYmZjK0VpYlpGL0ZrdHg2UT09