Optical/UV/X-ray Insights into the RL--RQ Dichotomy

TL;DR

This study investigates the differences and overlaps between radio-loud and radio-quiet quasars using optical, UV, and X-ray data, revealing distinct populations and a potential continuum with shared properties.

Contribution

It identifies specific optical/UV/X-ray characteristics that distinguish RL from RQ quasars and proposes a lower luminosity limit for RL quasars with FRII morphology, highlighting a possible continuum.

Findings

RL quasars show larger FWHM H-beta and weaker FeII emission.

No soft X-ray excess or CIV blueshift in RL sources.

A luminosity threshold of log L(1.4GHz)=31.6 erg/s/Hz for FRII morphology.

Abstract

We explore the relationship between radio-loud (RL) and radio-quiet (RQ) quasars using a set of optical/UV/X-ray measures that are quite independent of radio measures. We find RL sources to show larger average FWHM H-beta, weaker FeII emission, no soft X-ray excess and no CIV blueshift - all characteristics manifested by a large fraction of RQ quasars (that we call Population A). We find that log L (1.4Ghz) = 31.6 [ergs/s/Hz] (or R=70) is the lower limit for RL quasars showing FRII morphology. We find no evidence for a hidden FRII population below this level. We conclude that RL sources are a distinct quasar population that may also include 30-40 percent of RQ sources which apparently show similar geometry and kinematics (what we call Population B). This RQ overlap, if not coincidental, may include inactive RL quasars as well as quasars with geometry/kinematics similar to RL sources but where RL activity is inhibited in some way (e.g. host morphology, BH spin).