Relativistic beaming effects in the spectra of cores and hotspots in radiogalaxies and quasars

We present the results of multiwavelength observations of cores and hotspot s, at L, C, X and U bands with the Very Large Array, of a matched sample of radio galaxies and quasars selected from the Molonglo Reference Catalogue. We use these observations to determine the spectra of cores and hotspots, and test the unified scheme for radio galaxies and quasars. Radio cores hav e been detected at all wavelengths in all of the quasars in our sample, whe reas only similar to 50 per cent of the galaxies have cores detected in at least one of the wavelengths. The degree of core prominence in this sample is consistent with the unified scheme for radio galaxies and quasars. A com parison of the distributions of the two-point spectral index of the cores i n our sample of lobe-dominated quasars, with the distributions in a matched sample of core-dominated quasars, shows that the distributions for these t wo classes are significantly different, and this is consistent with the exp ectations of the unified scheme. The difference in the spectral indices of the two hotspots on opposite sides is also significantly larger for quasars than for radio galaxies, as is expected in the unified scheme. We also inv estigate the relationship between the spectral index of the hotspots and th e redshift or luminosity fur our sample of sources.