A statistical study of flat-spectrum radio sources at 966 MHz

Abstract

A sample of 36 flat-spectrum radio sources has been observed at 966 MHz with a resolution of ∼0.5 arcsec. Sixty-seven per cent of them showed evidence of extended emission several arcsec from an unresolved nucleus. Typically this emission constitutes 10 per cent of the total flux at 1 GHz. Our results show that most of the sources have asymmetric double structure. Interpreting this in terms of the relativistic jet model requires bulk relativistic motions up to several hundred kpc from the nucleus. The ratio of flux from the extended component to that from the nucleus is compared with what is expected from the model and found to be in rough quantitative agreement. The presence of extended emission, variability and spectral type are found to be correlated, and possible explanations for this are sought in terms of the relativistic jet model.