Nature and evolution of powerful radio galaxies and their link with the quasar luminosity function

TL;DR

This study uses a large sample of FRII radio galaxies from the FIRST survey to link their properties with quasar luminosity functions, revealing insights into jet origins and feedback mechanisms across cosmic time.

Contribution

It provides the largest FRII sample to date and connects radio galaxy populations with quasar activity and feedback, offering a comprehensive model of their evolution.

Findings

The observed FRII density matches known quasar populations.

High-redshift jets are more often quenched within 100 kpc.

Most powerful jets originate from radiatively efficient accretion flows.

Abstract

Current wide-area radio surveys are dominated by active galactic nuclei, yet many of these sources have no identified optical counterparts. Here we investigate whether one can constrain the nature and properties of these sources, using Fanaroff-Riley type II (FRII) radio galaxies as probes. These sources are easy to identify since the angular separation of their lobes remains almost constant at some tens of arcseconds for z>1. Using a simple algorithm applied to the FIRST survey, we obtain the largest FRII sample to date, containing over ten thousand double-lobed sources. A subset of 459 sources is matched to SDSS quasars. This sample yields a statistically meaningful description of the fraction of quasars with lobes as a function of redshift and luminosity. This relation is combined with the bolometric quasar luminosity function, as derived from surveys at IR to hard X-ray frequencies, and a disc-lobe correlation to obtain a robust prediction for the density of FRIIs on the radio sky. We find that the observed density can be explained by the population of known quasars, implying that the majority of powerful jets originate from a radiatively efficient accretion flow with a linear jet-disc coupling. Finally, we show that high-redshift jets are more often quenched within 100 kpc, suggesting a higher efficiency of jet-induced feedback into their host galaxies.