A photometric study of the field around the candidate recoiling/binary black hole SDSS J092712.65+294344.0

We present a photometric far-ultraviolet (FUV) to Ks-band study of the field around quasar SDSS J092712.65+294344.0. The SDSS spectrum of this object shows various emission lines with two distinct redshifts, at z = 0.699 and 0.712. Because of this peculiar spectroscopic feature, this source has been proposed as a candidate recoiling or binary black hole. A third alternative model involves two galaxies moving in the centre of a rich galaxy cluster. Here, we present a study addressing the possible presence of such a rich cluster of galaxies in the SDSS J092712.65+294344.0 field. We observed the 3.6 × 2.6 arcmin2 field in the Ks band and matched the near-infrared data with the FUV and near-ultraviolet images in the Galaxy Evolution Explorer archive and the ugriz observations in the SDSS. From various colour-colour diagrams, we were able to classify the nature of 32 sources, only 6-11 of which have colours consistent with galaxies at z ≈ 0.7. We compare these numbers with the surface density of galaxies, stars and quasars and the expectations for typical galaxy clusters both at low and high redshift. Our study shows that the galaxy cluster scenario is in clear disagreement with the new observations. © 2009 RAS.