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

TL;DR

This study uses multi-wavelength photometry to investigate the environment around the quasar SDSS J092712.65+294344.0, testing the hypothesis of a galaxy cluster and finding evidence against it, thus informing the nature of the black hole candidate.

Contribution

The paper provides a detailed photometric analysis across multiple bands to assess the presence of a galaxy cluster around the quasar, challenging previous cluster-based models for its peculiar spectral features.

Findings

Few galaxies at z~0.7 in the field, inconsistent with a rich galaxy cluster.

Surface density of sources does not match expectations for a cluster environment.

Results support the black hole recoil or binary scenario over the cluster hypothesis.

Abstract

We present a photometric 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 z=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 3.6x2.6 square arcmin field in the Ks-band and matched the NIR data with the FUV and NUV images in the GALEX 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 & 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.