BAT AGN Spectroscopic Survey -- XV: The High Frequency Radio Cores of Ultra-hard X-ray Selected AGN

TL;DR

This study uses high-frequency radio imaging to analyze the cores of 100 low-redshift AGN selected by hard X-ray emission, revealing high detection rates and insights into their radio and X-ray properties.

Contribution

It provides the first high-resolution 22 GHz radio imaging survey of Swift-BAT selected AGN, characterizing their radio morphologies and testing correlations with physical parameters.

Findings

96% radio core detection rate at 22 GHz

Radio morphology does not clearly distinguish emission origin

X-ray luminosity correlates with jet-like radio morphology

Abstract

We have conducted 22 GHz radio imaging at 1" resolution of 100 low-redshift AGN selected at 14-195 keV by the Swift-BAT. We find a radio core detection fraction of 96%, much higher than lower-frequency radio surveys. Of the 96 radio-detected AGN, 55 have compact morphologies, 30 have morphologies consistent with nuclear star formation, and 11 have sub-kpc to kpc-scale jets. We find that the total radio power does not distinguish between nuclear star formation and jets as the origin of the radio emission. For 87 objects, we use optical spectroscopy to test whether AGN physical parameters are distinct between radio morphological types. We find that X-ray luminosities tend to be higher if the 22 GHz morphology is jet-like, but find no significant difference in other physical parameters. We find that the relationship between the X-ray and core radio luminosities is consistent with the $L_R/L_X \sim 10^{-5}$ of coronally active stars. We further find that the canonical fundamental planes of black hole activity systematically over-predict our radio luminosities, particularly for objects with star formation morphologies.