The evolution of radio sources from complete samples
ASTROPHYS SPACE SC L 226 (1998) 179-184
Abstract:
From new complete samples of radio sources selected at low flux limits in low radio frequency, which give significantly improved coverage of the luminosity-redshift plane, we are able to decouple dependencies of source properties on redshift, from those depending on luminosity. We describe, with particular reference to the unification of radio galaxies and quasars, trends in linear size and also discuss core properties of these objects.A sample of 6C radio sources designed to find objects at redshift > 4: the radio data
ArXiv astro-ph/9707336 (1997)
Abstract:
We describe the selection of a sample of 34 radio sources from the 6C survey (Hales, Baldwin & Warner 1993) from a region of sky covering 0.133 sr. The selection criteria for this sample, hereafter called 6C*, were chosen to optimise the chances of finding radio galaxies at redshift z > 4. Optical follow-up observations have already led to the discovery of the most distant known radio galaxy at z = 4.41 (Rawlings et al. 1996). We present VLA radio maps and derive radio spectra for all the 6C* objects.A complete sample of quasars from the 7C redshift survey
ArXiv astro-ph/9704163 (1997)
Abstract:
We present details of a new sample of radio-loud quasars drawn from 0.013 sr of the 7C Redshift Survey. This sample is small (21 quasars) but complete in that every object with an unresolved nucleus and/or broad emission lines with S(151MHz) > 0.5 Jy has been discovered. The dependence of the quasar fraction with redshift and radio luminosity is investigated, providing new evidence supporting the unification of radio-loud quasars and powerful radio galaxies. This 7C sample is compared with optically-selected quasars, in order to determine whether there are systematic biases in the different selection techniques. There are no lightly reddened (Av approx. 1) quasars in our sample amongst the 14 with z < 2. The discovery of a reddened quasar at z = 2.034 and its implications are discussed. A tight correlation between radio luminosity and optical/near infrared continuum luminosity for a subset of the sample is also found.Evidence for a black hole in a radio-quiet quasar nucleus
ArXiv astro-ph/9606102 (1996)
Abstract:
We present the first milli-arcsecond resolution radio images of a radio-quiet quasar, detecting a high brightness temperature core with data from the VLBA. On maps made with lower-frequency data from MERLIN and the VLA jets appear to emanate from the core in opposite directions, which correspond to radio-emission on arcsecond scales seen with the VLA at higher frequencies. These provide strong evidence for a black-hole--based jet-producing central engine, rather than a starburst, being responsible for the compact radio emission in this radio-quiet quasar.A radio galaxy at redshift 4.41
Nature 383:6600 (1996) 502-505