The final candidate from the JVAS/CLASS search for 6-15 arcsec image separation lensing

Abstract

A search for 6-15 arcsec image separation lensing in the Jodrell Bank-Very Large Array Astrometric Survey (JVAS) and the Cosmic Lens All-Sky Survey (CLASS) by Phillips et al. found 13 group and cluster gravitational lens candidates. Through radio and optical imaging and spectroscopy, Phillips et al. ruled out the lensing hypothesis for 12 of the candidates. In this paper, new optical imaging and spectroscopy of J0122+427, the final lens candidate from the JVAS/CLASS 6-15 arcsec image separation lens search, are presented. This system is found not to be a gravitational lens, but is just two radio-loud active galactic nuclei that are separated by ∼10 arcsec on the sky and are at different redshifts. Therefore, it is concluded that there are no gravitational lenses in the JVAS and CLASS surveys with image separations between 6-15 arcsec. This result is consistent with the expectation that group- and cluster-scale dark matter haloes are inefficient lenses due to their relatively flat inner density profiles. © 2010 The Author Monthly Notices of the Royal Astronomical Society © 2010 RAS.