Radio Dichotomy in Quasars with H$\beta$ FWHM greater than $15,000$ km\,s$^{-1}$

TL;DR

This study reveals a high radio-loud fraction in high broad line quasars with H$eta$ FWHM over 15,000 km/s, linking brighter accretion disks and jet formation, and highlighting differences from non-HBL quasars.

Contribution

It provides the first detailed analysis of the radio-loud fraction in high broad line quasars and its relation to accretion properties and jet activity.

Findings

RLF is approximately 57% in high broad line quasars.

RL quasars have higher optical continuum luminosity.

RL quasars show stronger [O III] emission lines.

Abstract

It has been inferred from large unbiased samples that $10\%$-$15\%$ of all quasars are radio-loud (RL). Using the quasar catalog from the Sloan Digital Sky Survey, we show that the radio-loud fraction (RLF) for high broad line (HBL) quasars, containing H$\beta$ FWHM greater than $15,000$ km s$^{-1}$, is $\sim 57 \%$. While there is no significant difference between the RL and radio-quiet (RQ) populations in our sample in terms of their black hole mass, Eddington ratio, and covering fraction (CF), optical continuum luminosity of the RL quasars are higher. The similarity in the distribution of their CF indicates that our analysis is unbiased in terms of the viewing angle of the HBL RL and RQ quasars. Hence, we conclude that the accretion disc luminosity of the RL quasars in our HBL sample is higher, which indicates a connection between a brighter disc and a more prominent jet. By comparing them with the non-HBL H$\beta$ broad emission line quasars, we find that the HBL sources have the lowest Eddington ratios in addition to having a very high RLF. That is consistent with the theories of jet formation, in which jets are launched from low Eddington ratio accreting systems. We find that the [O III] narrow emission line is stronger in the RL compared to RQ quasars in our HBL sample, which is consistent with previous findings in the literature, and may be caused by the interaction of the narrow line gas with the jet.