Forecasts on Anisotropic Cosmic Birefringence Constraints for CMB Experiment in the Northern Hemisphere

TL;DR

This paper forecasts the potential constraints on anisotropic cosmic birefringence from a future Northern Hemisphere CMB experiment, demonstrating that larger telescopes and multi-frequency data merging can significantly improve sensitivity.

Contribution

It introduces a simulation-based forecast for anisotropic cosmic birefringence detection using a quadratic estimator in a planned Northern Hemisphere CMB experiment, highlighting the impact of telescope size and data merging methods.

Findings

Small aperture telescope can constrain $A_{CB}$ to 0.017 at 2σ.

Large aperture telescope improves constraint to 0.0062 at 2σ.

Merging multi-frequency data enhances constraint by about 10%.

Abstract

The study of cosmic birefringence through Cosmic Microwave Background (CMB) experiments is a key research area in cosmology and particle physics, providing a critical test for Lorentz and CPT symmetries. This paper focuses on an upcoming CMB experiment in the mid-latitude of the Northern Hemisphere, and investigates the potential to detect anisotropies in cosmic birefringence. Applying a quadratic estimator on simulated polarization data, we reconstruct the power spectrum of anisotropic cosmic birefringence successfully and estimate constraints on the amplitude of the spectrum, $A_{\mathrm{CB}}$, assuming scale invariance. The forecast is based on a wide-scan observation strategy during winter, yielding an effective sky coverage of approximately 23.6%. We consider two noise scenarios corresponding to the short-term and long-term phases of the experiment. Our results show that with a small aperture telescope operating at 95/150GHz, the $2\sigma$ upper bound for $A_{\mathrm{CB}}$ can reach 0.017 under the low noise scenario when adopting the method of merging multi-frequency data in map domain, and merging multi-frequency data in spectrum domain tightens the limit by about 10%.A large-aperture telescope with the same bands is found to be more effective, tightening the $2\sigma$ upper limit to 0.0062.