Simultaneous determination of the cosmic birefringence and miscalibrated polarization angles II: Including cross frequency spectra

TL;DR

This paper introduces a method to simultaneously estimate cosmic birefringence and polarization angle miscalibrations using both auto and cross frequency spectra of CMB polarization data, improving accuracy.

Contribution

It extends previous auto spectrum methods by incorporating cross frequency spectra, enabling more precise simultaneous determination of birefringence and calibration angles.

Findings

Reduced uncertainties in angle estimations by over a factor of two.

Effective separation of cosmic birefringence from instrumental miscalibration.

Enhanced analysis framework for future CMB polarization measurements.

Abstract

We develop a strategy to determine the cosmic birefringence and miscalibrated polarization angles simultaneously using the observed $EB$ polarization power spectra of the cosmic microwave background and the Galactic foreground emission. We extend the methodology of Y. Minami et al. (Prog. Theor. Exp. Phys. $\mathbf{2019}$, 083E02, 2019), which was developed for auto frequency power spectra, by including cross frequency spectra. By fitting one global birefringence angle and independent miscalibration angles at different frequency bands, we determine both angles with significantly smaller uncertainties (by more than a factor of two) compared to the auto spectra.