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

¹ Osservatorio di Radioastronomia–INAF, Bologna, via P. Gobetti 101, 40129 Bologna, Italy
e-mail: bondi@ira.inaf.it
² Instituto de Astrofísica de Andalucía–CSIC, PO Box 3004, 18008 Granada, Spain
³ Osservatorio Astronomico di Roma–INAF, via Frascati 33, 00040 Monte Porzio Catone, Roma, Italy
⁴ Department of Physics & Astronomy, University of Iowa, Iowa City, IA 52245, USA

Received: 21 December 2015
Accepted: 12 February 2016

Abstract

The sources SDSS J113126.08-020459.2 and SDSS J110851.04+065901.4 are two double-peaked [O III] emitting active galactic nuclei (AGNs), 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 M_⊙ yr^-1, 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.