On Asymmetries in Powerful Radio Sources and the Quasar/Galaxy Unification

Abstract

We utilize the distributions of fractional separation difference (x) as asymmetry parameter, linear size (D) and core-to lobe luminosity ratio (R) as orientation indicators, to investigate a consequence of radio source orientation and relativistic beaming effects in a sample of powerful non-symmetric extragalactic radio sources. In this scenario, radio sources viewed at small orientation angles to the line-of-sight are expected to show a high degree of asymmetry in observed radio structures due to relativistic beaming, with foreshortened projected linear sizes. A simple consequence of this is the x−D anti-correlation. Results show a tight correlation (r>0.8) between the total and core radio luminosities and a clear x−D anti-correlation (r∼−0.5). The observed x−D anti-correlation is consistent with average orientation angle ϕ ≈ 48^∘ and a maximum Lorentz factor γ∼ 2 for the sample, with minimum angular separation of 26 ^∘ between radio galaxies and quasars. However, there is no clear x−R correlation. While the results are consistent with quasar/galaxy unification via orientation, intrinsic asymmetry also seems to play a major role.