Mitigating half-wave plate systematics at the map-making level: calibration requirements for LiteBIRD

Raffuzzi, N., Carones, A., Monelli, M., Giardiello, S. and Pagano, L. 2026. Mitigating half-wave plate systematics at the map-making level: calibration requirements for LiteBIRD. Journal of Cosmology and Astroparticle Physics 2026 (8) , 053. 10.1088/1475-7516/2026/08/053

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Abstract

Although half-wave plates (HWPs) are becoming a popular choice of polarization modulators for cosmic microwave background (CMB) experiments, their non-idealities can introduce systematic effects that should be carefully characterized and mitigated. One possible mitigation strategy is to incorporate information about the non-idealities at the map-making level, which helps to reduce the HWP-induced distortions of the reconstructed CMB. Nevertheless, the non-idealities can only be known with finite precision. In this paper we investigate the consequences of discrepancies between their true frequency profiles and those assumed by the map-maker. We present an end-to-end framework, including a blind component-separation step, and use it to translate these discrepancies into a bias on the tensor-to-scalar ratio, r, for the LiteBIRD satellite mission. We subsequently derive realistic and conservative measurement requirements for accurately characterizing the HWP non-idealities to ensure they do not compromise LiteBIRD's ambitious scientific goals. We find that the obtained results are robust against sky models with varying complexity.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Physical, Chemical & Environmental Sciences Schools > Physics and Astronomy
Additional Information:	For full author list see article webpage https://doi.org/10.1088/1475-7516/2026/08/053
Publisher:	IOP Publishing
Date of First Compliant Deposit:	1 September 2026
Date of Acceptance:	8 June 2026
Last Modified:	01 Sep 2026 14:01
URI:	https://orca.cardiff.ac.uk/id/eprint/189315

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