Revealing dual radio sources in a sub-kpc-scale binary active galactic nucleus candidate

Abstract

We present new VLA and e-MERLIN imaging of a sub-kpc-scale binary active galactic nuclei (AGN) candidate. Two unresolved radio sources of similar luminosity around 1022 WHz−1 are identified in ∼35 hrs of e-MERLIN 6cm imaging. These radio sources have an angular separation and position angle of 0.19±0.06” and PA 22±10○, corresponding to a projected separation of 0.95±0.29 kpc at the epoch of the source. Our results suggest the presence of a kpc-scale active black hole pair hosted by two galaxies in the late stage of a merger at z = 0.35. This work follows Woo et al (2014) which presented two optical sources with a similar separation and position angle, and a velocity separation of 200 km s−1. Our target adds to the currently limited sample of close-separation binary AGN that will aid in understanding the frequency of mergers and the stochastic gravitational wave background.