Finding binary active galactic nuclei candidates by the centroid shift in imaging surveys

II. Testing the method with SDSS J233635.75-010733.7

Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, PO Box 918-3, 100049 Beijing PR China
e-mail: liuyuan@ihep.ac.cn

Received: 4 March 2016
Accepted: 27 June 2016

Abstract

We have previously proposed selecting binary active galactic nuclei (AGNs) candidates using the centroid shift of the images that is induced by the non-synchronous variations of the two nuclei. In this paper, a known binary AGN (SDSS J233635.75-010733.7) is employed to verify the functioning of this method. Using 162 exposures in the R band of the Palomar Transient Factory (PTF), an excess of dispersion in the positional distribution of the binary AGN is detected, although the two nuclei cannot be resolved in the images of PTF. We also propose a new method to compare the position of the binary AGN in PTF g and R band and find that the difference is highly significant even with only 20 exposures. This new method is efficient for two nuclei with different spectral energy distributions such as type I + type II AGN or an off-set AGN. Large-scale surveys such as the Panoramic Survey Telescope and Rapid Response System, and the Large Synoptic Survey Telescope are expected to discover a large sample of binary AGN candidates with these methods.