Polarization transfer in pulsar magnetosphere

Propagation of radio waves in the ultrarelativistic magnetized electronpositron plasma of pulsar magnetosphere is considered. Polarization state of the original natural waves is found to vary markedly on account of the wave mode coupling and cyclotron absorption. The change is most pronounced when the regions of mode coupling and cyclotron resonance approximately coincide. In cases when the wave mode coupling occurs above and below the resonance region, the resultant polarization appears essentially distinct. The main result of the paper is that in the former case the polarization modes become non-orthogonal. The analytical treatment of the equations of polarization transfer is accompanied by the numerical calculations. The observational consequences of polarization evolution in pulsar plasma are discussed as well.