Statistical Tests of the Unification Scheme for High Luminosity Double Radio Sources |
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Authors: | AA Ubachukwu |
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Institution: | (1) Regular Associate of the Abdus Salam ICTP, Trieste, Italy;(2) Department of Physics and Astronomy, University of Nigeria, Nsukka, Nigeria |
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Abstract: | We have carried out some statistical tests of relativistic beaming and radio source orientation scenarios using the core dominance
parameter Rand linear size D of a recent sample of double-lobed quasars and radio galaxies as orientation indicators. Our results show that the maximum
Doppler boosting occurs within a cone angle of ∼ 13°corresponding to an optimum Lorentz factor of ∼ 5. On the average, quasar cores appear to be boosted by a factor of ∼ 10 relative
to those of radio galaxies. In general, we found that quasars lie at closer angles to the line of sight than radio galaxies
with median values of 28° and 51°respectively, implying a relative foreshortening factor of ∼ 2. These results are consistent with the simple relativistic
beaming and orientation-based unification hypotheses in which quasars are the beamed counterparts of powerful radio galaxies
which form the isotropic parent population. The results show a strong evidence that orientation of source axis with respect
to the line of sight is a crucial parameter in the classification schemes for radio sources.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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