General relativistic contribution to polarization of the cosmic microwave background anisotropy - art. no. 027301

We solve the wave equation for the electromagnetic field tensors associated with the cosmic microwave background radiation (CMBR) photons in a univers e with scalar metric perturbations. We show that the coupling of the electr omagnetic fields with the curvature associated with the scalar perturbation s gives rise to an optical rotation of the microwave background photons. Th e magnitude of the gravitationally generated V-Stokes parameter anisotropy Delta (V) is however very small compared to the linear polarization caused by Thomson scattering.