Statistical analyses of quasars with resolved radio components. III. Evolutionary properties of the sizes of components. IV. Evolutionary properties of radio polarization parameters

Abstract The sizes of 64 radio components of quasars have been determined using their angular diameters and redshifts. No significant correlation is found between their sizes and their mutual separation whether different initial luminosity ranges are considered separately or together. This result implies that the sizes of the components do not change much during the lifetime of quasars with a resolved radio structure. A statistical analysis has been made on the polarization properties of those quasars in which the Faraday depolarization is mainly responsible for the inverse relationship between the degree of polarization and the wavelengrh. Our results are: (1) There is no significant correlation between λ 1 2 and D ; there is, however, an obvious correlation between λ 1 2 2 d ∗ and D ∗ . (2) The statistical relation between m max and D shows that the random component of the magnetic field increases as the quasar evolves. (3) There is no evident evolutionary trend in the magnetic field given by minimizing the total energy. (4) The representation by a Gaussian of the Faraday depth distribution makes it obvious that the thermal electron density in the components decreases as the quasar evolves: n e = 2.24 × 10 −2 × 10 −0.071 D ∗