Synchrotron radio emission in radio-quiet AGNs

TL;DR

This paper proposes that radio-quiet AGNs emit synchrotron radiation from shock-accelerated particles, explaining their radio and X-ray luminosity ratios and the observed anti-correlation between radio-loudness and Eddington ratio.

Contribution

It introduces a shock-based synchrotron emission model for radio-quiet AGNs, linking radio and X-ray emissions and explaining observed luminosity trends.

Findings

Radio to X-ray luminosity ratio is much less than one in radio-quiet AGNs.

Predicted trends match the observed anti-correlation between radio-loudness and Eddington ratio.

Model accounts for synchrotron emission in radio-quiet AGNs based on shock acceleration.

Abstract

The basic mechanism responsible for radio emission in radio-loud active galactic nuclei (AGNs) is assumed to be synchrotron radiation. We suggest here that radio emission in radio-quiet objects is also due to synchrotron radiation of particles accelerated in shocks. We consider generic shocks and study the resulting synchrotron properties. We estimate the synchrotron radio luminosity and compare it with the X-ray component produced by inverse Compton emission. We obtain that the radio to X-ray luminosity ratio is much smaller than unity, with values typical of radio-quiet sources. The predicted trends on source parameters, black hole mass and accretion rate, may account for the anticorrelation between radio-loudness and Eddington ratio observed in different AGN samples.