Correlation Between Radio Loudness and the Eddington Ratio in Quasars

Abstract

Quasars can be categorized into radio-loud and radio-quiet populations based on radio properties. The physical mechanisms underlying this dichotomy have long been an active area of investigation. In this work, we analyze multi-wavelength data from 851 quasars matched between the SDSS DR14 and FIRST catalogs, requiring emission line measurements with signal-to-noise ratios > 3, we fit quasar optical continuum spectra and compute the radio loudness, luminosities, and Eddington ratios. We classify quasars as radio-loud or radio-quiet using a dividing line of $\log L_{6\mathrm{cm}}=-2.7\log R+44.3$. We find that the distribution of the Eddington ratio and radio luminosity is different between the radio-loud and radio-quiet quasars, and the correlation between the Eddington ratio and radio loudness is disparate as well. The Eddington ratio shows a weakly positive correlation with radio loudness in both the whole sample and radio-loud quasars, which imply that the Eddington ratio contributes to the radio loudness but it is not the dominant factor and that additional factors influence relativistic jet production in radio-loud quasars. However, the Eddington ratio is anti-correlated with radio loudness in radio-quiet quasars, potentially related to the properties of the accretion disk.