New Constraints on Cosmic Birefringence from Upcoming CMB Experiment

A recent paper titled "Forecasts on Anisotropic Cosmic Birefringence Constraints for CMB Experiment in the Northern Hemisphere" by Yiwei Zhong et al. presents findings relevant to the study of cosmic birefringence through Cosmic Microwave Background (CMB) experiments. The research focuses on an upcoming CMB experiment located in the mid-latitude of the Northern Hemisphere, aiming to detect anisotropies in cosmic birefringence, which is significant for testing Lorentz and CPT symmetries in physics.

The authors applied a quadratic estimator on simulated polarization data to reconstruct the power spectrum of anisotropic cosmic birefringence. They estimated constraints on the amplitude of the spectrum, denoted as $A_{\mathrm{CB}}$, under the assumption of scale invariance. The experiment is designed to utilize a wide-scan observation strategy during winter, achieving an effective sky coverage of approximately 23.6%.

Two noise scenarios were considered: short-term and long-term phases of the experiment. The results indicate that a small aperture telescope operating at 95/150 GHz can reach a $2\sigma$ upper bound for $A_{\mathrm{CB}}$ of 0.017 under low noise conditions. Furthermore, merging multi-frequency data in the map domain tightens this limit by about 10%. A large-aperture telescope with the same frequency bands is shown to be more effective, tightening the $2\sigma$ upper limit to 0.0062.

These findings are crucial as they enhance our understanding of cosmic birefringence and its implications for fundamental physics, potentially impacting theories related to the early universe and the nature of cosmic structures. The paper can be accessed through arXiv with the identifier arXiv:2409.01098.