Cosmic optical activity from an inhomogeneous Kalb–Ramond field

The effects of introducing a harmonic spatial inhomogeneity into the Kalb–Ramond field, interacting with the Maxwell field according to a 'string-inspired' proposal made in an earlier study are investigated. We examine, in particular, the effects on the polarization of synchrotron radiation from cosmologically distant (i.e. of redshift >2) galaxies, as well as the relation between the electric and magnetic components of the radiation field. The rotation of the polarization plane of linearly-polarized radiation is seen to acquire an additional contribution proportional to the square of the frequency of the dual Kalb–Ramond axion wave, assuming that it is far smaller compared to the frequency of the radiation field.