... ATNF Home . ... Propagation-induced circular polarization in synchrotron sources . ... The natural wave modes of a gas of highly relativistic particles are close to linearly polarized for nearly all angles of propagation and for frequencies typical of synchrotron emission by these highly relativistic particles (Sazonov 1969; Melrose 1997a). ... In general the modes are elliptically polarized with the ellipticity determined by the ratio of the number densities of cold and highly relativistic...