Improving Cosmic Birefringence Constraints via Delensing
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arXiv
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| Format: | Preprint |
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2025
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| author | Lonappan, Anto Idicherian |
| author_facet | Lonappan, Anto Idicherian |
| contents | 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 $β= 0.35^\circ$, delensing reduces the lensing-induced variance in the EB power spectrum, yielding an improvement in sensitivity of approximately 10% at 6 $μ$K-arcmin noise and 25-40% at lower noise levels. For the anisotropic case, using simulations at 1 $μ$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 $N_{(0)}$ bias and a 30% improvement in the constraints on the amplitude $A_{CB}$. 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. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2503_04708 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Improving Cosmic Birefringence Constraints via Delensing Lonappan, Anto Idicherian Cosmology and Nongalactic Astrophysics 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 $β= 0.35^\circ$, delensing reduces the lensing-induced variance in the EB power spectrum, yielding an improvement in sensitivity of approximately 10% at 6 $μ$K-arcmin noise and 25-40% at lower noise levels. For the anisotropic case, using simulations at 1 $μ$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 $N_{(0)}$ bias and a 30% improvement in the constraints on the amplitude $A_{CB}$. 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. |
| title | Improving Cosmic Birefringence Constraints via Delensing |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2503.04708 |