A suspected Dark Lens revealed with the e-EVN

Abstract

The e-VLBI technique offers a unique opportunity for users to probe the milliarcsecond (mas) scale structure of unidentified radio sources, and organise quick follow-up observations in case of detection. Here we report on e-EVN results for a peculiar radio source that has been suggested to act as a gravitational lens. However the lensing galaxy has not been identified in the optical or the IR bands so far. Our goal was to look for an active galactic nucleus (AGN) in this suspected dark lens system. The results indicate strong AGN activity, and rule out the possibility that the radio source itself is gravitationally lensed.