High-resolution imaging of the double QSO 2345 + 007 - Evidence for subcomponents

Abstract

We have observed, at the CFH telescope with the time-resolved imaging mode of the ESA Photon Counting Detector, the field of the double QSO 2345+007 in the UV band. Integrated images have a 0.55"-0.60" resolution; by using recentering and selection algorithms, we obtain images reaching 0.4" resolution. From several lines of evidence, we show that component B is resolved and elongated in a direction almost perpendicular to the AB direction. A further improvement in resolution has been achieved by applying image restoration techniques. The results show that component B is made of two subcomponents of roughly equal intensity, 0.36" apart. The line of their centers makes a slight (~12^deg^) angle with the AB direction. At least one of the two subcomponents, B2, is elongated in a direction perpendicular to the AB direction and is responsible for the observed elongation of component B. The magnitude difference between A and B is 1.70 mag. A comparison with previously published data suggests some variability in the system. This result and the specific configuration described above give new support for the gravitational lens hypothesis: A and the two subcomponents of B, B1 and B2, are different images of the same source quasar, with B2 being better interpreted as an unresolved multiple component image than a really extended object. The AB splitting would result from the action of a single galaxy and its cluster as a whole, while the B_1_ B_2_ splitting requires the action of another 5 x 10^10^ M_sun_ galaxy.