1306.2087 (Ashok K. Singal)

Discordance of the unified scheme with observed properties of quasars and high-excitation galaxies in the 3CRR sample    [PDF]

Ashok K. Singal

We examine the consistency of the unified scheme of radio galaxies and quasars with their observed number and size distributions in the 3CRR sample. We have separated the low-excitation galaxies from the high-excitation ones, as the former might not harbour a quasar within and thus may not be partaking in the unified scheme models. It comes out that in the updated 3CRR sample, at low redshifts (z<0.5), the relative number of high-excitation galaxies and quasars roughly match the expectations from the popular orientation-based unified scheme model. However, a foreshortening in the observed sizes of quasars, a must in the orientation-based model, is not seen with respect to radio galaxies even when the low-excitation galaxies are excluded. This dashes the hope that the unified scheme might still work if one includes only the high-excitation galaxies. Even in the high redshift range (z>1), though there seems a foreshortening in the quasar sizes, the number of quasars there is too high compared with radio galaxies (all high-excitation ones only at those redshifts) than would be expected in unified scheme. Further we find that the relative number and size distributions of high-excitation galaxies and quasars in the 3CRR sample vary heavily over the sky. A Kolmogorov-Smirnov test shows that we can rule out at a 95% confidence level the null-hypothesis that the two types of sources (high excitation radio galaxies and quasars) belong to the same parent population, which we find to be very damaging evidence against unified scheme.

View original: http://arxiv.org/abs/1306.2087