Testing Cosmic Microwave Background Anomalies in E-mode Polarization with Current and Future Data

In this paper, we explore the power of the cosmic microwave background (CMB) polarization (E-mode) data to corroborate four potential anomalies in CMB temperature data: the lack of large angular-scale correlations, the alignment of the quadrupole and octupole (Q-O), the point-parity asymmetry, and the hemispherical power asymmetry. We use CMB simulations with noise representative of three experiments-the Planck satellite, the Cosmology Large Angular Scale Surveyor (CLASS), and the LiteBIRD satellite-to test how current and future data constrain the anomalies. We find the correlation coefficients rho between temperature and E-mode estimators to be less than 0.1, except for the point-parity asymmetry (rho = 0.17 for cosmic-variance-limited simulations), confirming that E-modes provide a check on the anomalies that is largely independent of temperature data. Compared to Planck component-separated CMB data (smica), the putative LiteBIRD survey would reduce errors on E-mode anomaly estimators by factors of similar to 3 for hemispherical power asymmetry and point-parity asymmetry, and by similar to 26 for lack of large-scale correlation. The improvement in Q-O alignment is not obvious due to large cosmic variance, but we found the ability to pin down the estimator value will be improved by a factor greater than or similar to 100. Improvements with CLASS are intermediate to these.

Automated summary

This paper investigates the use of cosmic microwave background (CMB) polarization data to confirm anomalies in CMB temperature data. It finds that the E-mode estimators provide a largely independent check on these anomalies, with correlation coefficients between temperature and E-mode estimators less than 0.1. The study also shows that future experiments like the LiteBIRD survey can significantly reduce errors in anomaly estimators, particularly for the lack of large-scale correlation. The improvement in other anomalies like Q-O alignment is less clear due to cosmic variance.