Transfer of polarized radiation in self-absorbed synchrotron sources. II - Treatment of inhomogeneous media and calculation of emergent polarization
As an extension of previous treatments of polarized radiation transfer in homogeneous synchrotron sources, a transfer procedure is derived, based on the coupled-wave formulation, which allows consideration of inhomogeneous sources. It is shown that plasma characteristic wave eccentricities in a source must be fairly large unless Faraday rotation per absorption depth is very large, and that coupling between characteristic waves can be strong in inhomogeneous self-absorbed sources. Calculations are made of the polarized radiation emergent from a source with a boundary of finite thickness. It is found that neglect of propagation effects in the source boundary introduces no significant errors at optically thin frequencies, but that below the self-absorption turnover the emergent polarization may depend significantly upon such effects. In particular, the sign of the circular polarization and the linear polarization position angle depend upon the absorption depth in the boundary region.