Polarization properties of extragalactic radio sources

Results are reported for a statistical analysis of a catalog of 510 extragalactic radio sources for which a minimum of three polarization observations at different wavelengths were published between 1965 and mid-1974. Histograms of mean spectral indices, mean polarization indices, redshifts, angular diameters, linear diameters, and rotation measures are plotted separately for all sources, sources without known identification, galaxies with no published redshifts, galaxies with known redshifts, quasars with no published redshifts, and quasars with known redshifts. The mean polarization index is defined on the basis of a simple synchrotron emission model and the observed spectral polarization. It is found that the mean polarization index is very well correlated with mean spectral index and that radio galaxies have steeper spectra than quasars in both their flux-density and polarization-index distributions.