On the circular polarisation of light from axion-photon mixing

Understand

From the analysis of measurements of the linear polarisation of visible light coming from quasars, the existence of large-scale coherent orientations of quasar polarisation vectors in some regions of the sky has been reported.

• Here, we show that this can be explained by the mixing of the incoming photons with nearly massless pseudoscalar (axion-like) particles in extragalactic magnetic fields.
• We present a new treatment in terms of wave packets and discuss its implications for the circular polarisation.