New estimators for anisotropic birefringence from CMB observations
Matteo Billi (Unibo)
Tuesday 13/04/2021 @ 14:00, Sala IV piano Battiferro
Parity-violating extensions of standard electromagnetism produce cosmic birefringence, the in vacuo rotation of the linear polarisation direction of a photon during propagation. We present the formalism for two new harmonic-based methods aimed at estimating the anisotropic birefringence effect from CMB polarised spectra: the first, based on the covariance of the TB spectrum, is sensitive to the variance of the birefringence anisotropies, whereas the second one, based on the covariance of the EB spectrum, is instead sensitive to both the variance and the spectrum of the birefringence anisotropies. We describe the properties of these new estimators and present preliminary results.