THE POLARIZATION-REDSHIFT RELATION IN RADIO GALAXIES

We analyze the properties of a sample of optically polarized radio gal axies with a wide range of redshifts. The galaxies were selected both from our survey and from the literature. The aim of this work is check ing whether high linear polarization is a general property of high red shift radio galaxies and how it depends on redshift. This provides a c ritical test on the suggestion that a considerable fraction of rest fr ame UV light in high redshift radio galaxies is scattered nuclear radi ation. Our results show that radio galaxies with z > 0.7 are strongly polarized and that there is a strong dependence of the degree of linea r polarization on the redshift. We discuss the possible origin of this correlation. Our results provide support to the validity of the Radio Quasar and Radio Galaxies unifying schemes.