SELECTION EFFECTS AND STRUCTURAL SYMMETRIES IN THE ORIENTATION BASED UNIFIED SCHEME

Abstract

Using the projected linear size, (D) as an orientation parameter, the armlength ratio, (Q) and the lobe-luminosity ratio, (R) as asymmetry parameters, we test the FR-II galaxies (Gs) and radio-loud quasar (Qs) unification scheme. Using the median values of our binned sample, our results, generally indicate that the D of the radio sources are smaller at higher redshifts z and at larger Q values, with the D of Qs smaller than those of Gs across all Q, z and R bins. Also, the D of Gs appear smaller for lower values of Q, if R ≤ 1.0 but become larger at higher values of Q if R > 1.0. For Qs, the D decreases with increasing Q, R and z. These results imply that the beaming effect is more important in Qs than in Gs. The D − R regression analyses for different Q and z subsamples suggest the importance of factors other than beaming and orientation in the interpretation of the evolution of these radio sources.