U2-2016
Host: Mario Zannoni
Title:
Non-standard signatures in CMB polarisation and the challenge of beam and HWP systematics for next-generation CMB experiments
Abstract:
In this seminar, I will focus on non-standard signatures in CMB polarisation, which may hint at phenomena beyond the standard models of cosmology (LCDM) and particle physics. Specifically, I will discuss the use of polarisation data to extend the statistical significance of CMB anomalies initially observed in temperature, and to constrain the effect of cosmic birefringence (CB), a signature predicted in parity-violating extensions of electromagnetism.
While the scientific motivation for observing CMB polarisation is robust, its measurement involves considerable technological challenges; in particular, accurate signal estimation depends on the stringent control of systematic effects. I will examine the impact of spurious signals on next-generation experiments, focusing on the complex interplay between half-wave plate (HWP) non-idealities and telescope beam patterns. A key objective is to quantify how these coupled systematics can bias the measurement of the cosmic birefringence effect. Finally, I will present results obtained using advanced Time-Ordered Data (TOD) simulations within the litebird_sim and TOAST frameworks, incorporating analytical beam models and full-sky harmonic convolutions. The discussion will cover ongoing work within the Simons Observatory (SO) and LiteBIRD collaborations, specifically addressing the characterisation of beam systematics in the SO Large Aperture Telescope (LAT) and the impact of Far Sidelobe (FSL) contamination on signal extraction for LiteBIRD. These results highlight the critical importance of high-fidelity instrumental modelling for the next decade of CMB cosmology.