Unveiling the radio counterparts of two binary AGN candidates: J1108+0659 and J1131-0204

TL;DR

This study used high-resolution radio and archival observations to investigate two candidate binary AGNs, confirming only one active nucleus in each, and revealing complex radio and star formation features.

Contribution

The paper provides the first high-resolution radio imaging analysis of these binary AGN candidates, clarifying their nuclear activity status.

Findings

Only one compact radio core detected in each source.

Extended radio emission indicates significant star formation obscured in UV.

Confirmed both candidates are not true binary AGNs, only single active nuclei.

Abstract

The sources SDSS\,J113126.08-020459.2 and SDSS\,J110851.04+065901.4 are two double-peaked [O III] emitting AGN, identified as candidate binary AGNs by optical and near infrared (NIR) observations. We observed the two sources with high resolution Very Long Baseline Interferometry (VLBI) using the European VLBI Network at 5\,GHz, reduced VLA observations at three frequencies available for one of the sources, and used archival HST observations. For the source SDSS\,J113126.08-020459.2, the VLBI observations detected only one single compact component associated with the eastern NIR nucleus. In SDSS\,J110851.04+065901.4, the VLBI observations did not detect any compact components, but the VLA observations allowed us to identify a possible compact core in the region of the north-western optical/NIR nucleus. In this source we find kpc-scale extended radio emission that is spatially coincident to the ultraviolet continuum and to the extended emission narrow line region. The UV continuum is significantly obscured since the amount of extended radio emission yields a star formation rate of about 110 \msunyr, which is an order of magnitude larger than implied by the observed ultraviolet emission. Our analysis confirms the presence of only one AGN in the two candidate binary AGNs.