Pulsars, transients and relativistic astrophysics

Abstract:

We use three samples (3CRR, 6CE and 6C*) to investigate the radio luminosity function (RLF) for the 'most powerful' low-frequency selected radio sources. We find that the data are well fitted by a model with a constant ca-moving space density at high redshift as well as by one with a declining co-moving space density above some particular redshift. This behaviour is very similar to that inferred for steep-spectrum radio quasars by Willott et al (1998) in Line with the expectations of Unified Schemes. We conclude that there is as yet no evidence for a 'redshift cutoff' in the co-moving space densities of powerful classical double radio sources, and rule out a art-off at z less than or similar to 2.5.

Abstract:

Orientation-based unified schemes for radio-loud quasars and radio galaxies are discussed in the light of a new complete sample of identified radio sources - the 7C Redshift Survey. Selected at the low radio frequency of 151 MHz this sample is free of orientation biases and together with the 3CRR sample allows a direct comparison of the properties of radio galaxies and quasars. The fraction of quasars in complete samples is used to estimate the opening angle of the putative obscuring torus. Correlations between the extended radio luminosity and the optical continuum and narrow emission line luminosities are presented and discussed in terms of the physical processes occurring in radio-loud AGN.