Constraints on cosmic birefringence using E-mode polarisation

A birefringent universe could show itself through a rotation of the plane of polarisation of the cosmic microwave background photons. This is usually investigated using polarisation B modes. Here we point out an independent method for extracting the birefringence angle using only temperature and E-mode signals. We forecast that, with an ideal cosmic-variance-limited experiment, we could constrain a birefringence angle of 0.3 degrees with 3 sigma statistical significance, which is close to the current constraints using B modes. We explore how this method is affected by the systematic errors introduced by the polarisation efficiency. In the future, this could provide an additional way of checking any claimed B-mode derived birefringence signature.

Automated summary

This paper investigates a method for exploring a birefringent universe through the rotation of the plane of polarization of cosmic microwave background photons. The authors propose an independent method for extracting the birefringence angle using only temperature and E-mode signals. They forecast that with an ideal experiment, a birefringence angle of 0.3 degrees can be constrained with 3 sigma statistical significance. Additionally, the authors explore the impact of systematic errors introduced by polarization efficiency and suggest this method as an additional way to verify claimed birefringence signatures derived from B modes.