paper

Improving Cosmic Birefringence Constraints via Delensing

arXiv:2503.04708 · doi:10.1088/1475-7516/2025/07/009

Abstract

We present a study on using delensing to enhance cosmic birefringence measurements based on full-sky, map-based simulations. In our analysis, we neglect foreground contamination and instrumental systematics to isolate the intrinsic impact of delensing on both isotropic and anisotropic birefringence. For the isotropic case, assuming a constant rotation angle of , delensing reduces the lensing-induced variance in the EB power spectrum, yielding an improvement in sensitivity of approximately 10% at 6 K-arcmin noise and 25-40% at lower noise levels. For the anisotropic case, using simulations at 1 K-arcmin noise, we reconstruct the birefringence angle for a scale-invariant spectrum and mitigate lensing bias by delensing, achieving a 50% reduction in the leading bias and a 30% improvement in the constraints on the amplitude . Our results demonstrate that delensing is an effective tool for enhancing the detectability of subtle parity-violating signals in the cosmic microwave background with forthcoming experiments such as the Simons Observatory, CMB-S4, and LiteBIRD.

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