Detection of Lens Candidates for the Double QSO Q2345+007

Abstract

Luminous objects associated with the 7.06\arcsec\ separation double quasar Q2345+007 have, until now, escaped detection. In this letter we present the results of the deepest known imaging of the region surrounding the quasar. The total exposure times were 47600 seconds in B${}_j$ (101 frames) and 32160 seconds in R (82 frames). The frames came from CFHT, CTIO, and KPNO. We detect a B${}_j$ = 25.0 mag galaxy (B${}_j$ -- R = 0.5 mag) in close proximity to the fainter QSO image, possibly at $z=1.49$ given by several absorption features in the QSO spectra. Furthermore, there is a 2.9$\sigma$ enhancement in the number density of faint galaxies ($24\le$ B${}_j$ $\le 28$, B${}_j-$ R $\le 1.5$) near the quasar and another 3.1$\sigma$ enhancement further away. These discoveries support the hypothesis that Q2345+007 is being lensed by one or more distant mass concentrations and may imply that compact ``clusters'' already exist at early epochs. We discuss several lens models for the system and the cosmological implications.

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