Hybridization of electric and magnetic responses in the effective axion background

We investigate the electromagnetic fields produced by the oscillating point electric or magnetic dipole placed in a spherical volume with a nonzero time-independent effective axion field. Our analytical solution shows that the fields outside the volume are a superposition of electric and magnetic dipole fields. Such multipole time-dependent generalization of the Witten effect can be realized in magnetoelectrics, topological insulators, or metamaterials providing a flexible probe of P- and T-symmetry-breaking phenomena in different electromagnetic structures.