Orateur
Description
Recent analyses of Planck polarization data have reported a hint of cosmic birefringence at the level of a $~3.6\sigma$ deviation from the parity-conserving standard cosmological model. At the same time, tensions between CMB data and large-scale structure observations can be alleviated by replacing the cosmological constant with dynamical dark energy. Ultralight axion-like particles can explain both signals by rotating the polarization plane of CMB photons and contributing to the background evolution via a time-varying equation of state.
In this talk, I will present a modified version of the Einstein-Boltzmann solver CLASS that self-consistently calculates parity-odd CMB power spectra for an axion dark energy model with a quadratic potential. This will, for the first time, allow a unified treatment that tracks the late-time evolution of the pseudo-scalar field and simultaneously predicts its impact on cosmological observables. I will show how different axion masses produce distinctive features in the CMB polarization power spectra.