The asymmetry of low-and high-redshift radio galaxies.

Using the published data on the GB/GB2 and 3C radio galaxies, we investigate the influence of the total radio luminosity and the redshift on the distributions of three structural parameters Q, M, L, which measure the asymmetry, bending and linear size of the radio source, respectively. We find that the high-redshift galaxies (z > 0.7) have much more asymmetrical and bent structures than do the high-luminosity low-redshift ones, and that among the low-redshift galaxies those that are more luminous have more symmetrical and straight structures than the weak ones. The numerical simulations consistently account for all of the observed properties using a model in which all variations of source structure are attributed to relative differences in the velocities of non-collinear plasmons (jets) simultaneously ejected in opposite directions from the core. The most probable reason for these velocity differences is the interaction between the plasmons and the galactic (intergalactic) medium, whose properties are modified essentially somewhere above z >= 0.7. The typical plasmon velocities are about 0.01c, if 10^-7^ yr is assumed as the standard plasmon age.