Ruling Out Compact Jets as the Dominant Source of Radio Emission in Radio-quiet, High Eddington-ratio Active Galactic Nuclei

Abstract

The origin of core radio emission in radio-quiet active galactic nuclei (AGNs) is still actively debated. General relativistic magnetohydrodynamics simulations often predict the launching of moderately large-scale jets from super-Eddington accretion flows, but this prediction seems at odds with observations indicating most high/super-Eddington AGNs appear radio quiet. Here, we use the ratio of radio to X-ray luminosities as a multiwavelength diagnostic to probe the origin of radio emission in a sample of 69 radio-quiet, high/super-Eddington AGNs with black-hole masses $M_{\mathrm{BH}}\sim 10^5-10^9{M}_{\odot }$. With this wide dynamic range in $M_{\mathrm{BH}}$, we adapt existing formalisms for how jetted radio emission and accretion-powered X-ray emission scale with black hole mass into the super-Eddington regime. We find that the radio/X-ray luminosity ratios observed across this $M_{\mathrm{BH}}$ range are inconsistent with a jet-dominated model for radio emission. We discuss how our results may instead be consistent with a corona-dominated radio emission origin with a contribution from outflows at higher accretion rates.

Accepted for publication in ApJ. 21 pages, 5 figures, 2 tables