The prevalence of FR I radio quasars

We present deep, multi-VLA-configuration radio images for a set of 18 quasars, having redshifts between 0.36 and 2.5, from the 7C quasar survey. Approximately one quarter of these quasars have FR I-type twin-jet structures and the remainder are a broad range of wide angle tail, fat double, classical double, core-jet and hybrid sources. These images demonstrate that FR I quasars are prevalent in the universe, rather than non-existent as had been suggested in the literature prior to the serendipitous discovery of the first FR I quasar a few years ago, the optically powerful ‘radio quiet’ quasar E 1821+643. Some of the FR I quasars have radio luminosities exceeding the traditional FR I / FR II break luminosity, however we find no evidence for FR II quasars with luminosities significantly below the break. We consider whether the existence of such high luminosity FR I structures is due to the increasingly inhomogeneous environments in the higher redshift universe.