paper

Forecasts of constraining isotropic cosmic birefringence on AliCPT-1

arXiv:2510.21221 · doi:10.1088/1475-7516/2026/02/079

Abstract

Cosmic birefringence (CB) is a promising probe of parity-violating physics beyond the Standard Model, characterized by the rotation of the linear polarization plane of cosmic microwave background (CMB) photons. This effect, quantified by the birefringence angle , generates non-zero and correlations that are otherwise absent in standard cosmology. However, instrumental miscalibration angles can mimic this signal, necessitating a joint estimation approach. In this work, we forecast the sensitivity of the AliCPT experiment, combined with Planck HFI data, on constraining the isotropic CB angle using a semi-analytical maximum-likelihood method. We simulate observations under various foreground complexities, rotation angles, and scanning strategies, and demonstrate that AliCPT can achieve an uncertainty of with one-year data, which will improve to after four years' observations. We also find that neglecting or mismodeling the foreground correlation will introduce significant biases, which can be alleviated under a clean but small sky patch.

Matches version accepted by JCAP; 22 pages, 9 figures, 7 tables; Major revision: adding Appendix D

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