Unification Scheme in Double Radio Sources: Bend Angle versus Arm Length Ratio Relations

Abstract

From radio source unification scheme, asymmetries are more pronounced in quasars than in radio galaxies. Using a sample of 625 double radio sources (316 radio galaxies and 309 quasars), we investigated the variations between bend angle, arm-length ratio and redshift. We find no significant correlation (0.045) between bend angle and redshift for the entire sample and at low z for radio galaxies while a weak correlation (0.121) between bend angle and redshift for quasars for the entire sampleis observed. A weak correlation (radio galaxies, r = 0.173 and quasars, r = 0.102) between the bend angle and arm-length ratio for the double radio sources used in this study is observed. Kharbet al. (2008) in their study of powerful classical double radio galaxies noted that this correlation could suggest that the environmental asymmetries that give rise to the arm- length ratio could be contributory to the misalignment angles in these sources. Quasars appear much more bent and misaligned. This is consistent with quasars being radio galaxies viewed at small angles.