The nuclear radio structure of X-ray bright AGN

TL;DR

This study uses high-resolution radio observations to show that the radio emission in X-ray bright AGN originates near the central black hole, not from star formation, clarifying the link between X-ray and radio emissions.

Contribution

First high-resolution radio imaging of a diverse sample of X-ray bright AGN, demonstrating the nuclear origin of their radio emission.

Findings

Radio emission is unresolved in all sources.

Radio luminosities are too high for star formation to be the main source.

Radio emission is closely linked to processes near the central black hole.

Abstract

The physical nature of the X-ray/radio correlation of AGN is still an unsolved question. High angular resolution observations are necessary to disentangle the associated energy dynamics into nuclear and stellar components. We present MERLIN/EVN 18cm observations of 13 X-raying AGN. The sample consists of Seyfert 1, Narrow Line Seyfert 1, and LINER-like galaxies. We find that for all objects the radio emission is unresolved and that the radio luminosities and brightness temperatures are too high for star formation to play an important role. This indicates that the radio emission in these sources is closely connected to processes that occur in the vicinity of the central massive black hole, also where the X-ray emission is believed to originate in.