The prevalence of FRI radio quasars

TL;DR

This study reveals that FRI-type radio quasars are common in the universe, challenging previous beliefs, with diverse radio morphologies observed across a range of redshifts and luminosities.

Contribution

The paper provides the first deep radio imaging survey showing the prevalence of FRI quasars and their diverse structures, including high-luminosity FRI sources.

Findings

Approximately 25% of quasars have FRI-type twin-jet structures.

FRI quasars are more common than previously thought.

Some FRI quasars exceed the traditional luminosity break.

Abstract

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 FRI-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 FRI 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 FRI quasar a few years ago, the optically powerful "radio quiet" quasar E1821+643. Some of the FRI quasars have radio luminosities exceeding the traditional FRI / FRII break luminosity, however we find no evidence for FRII quasars with luminosities significantly below the break. We consider whether the existence of such high luminosity FRI structures is due to the increasingly inhomogeneous environments in the higher redshift universe.