A suspected Dark Lens revealed with the e-EVN

TL;DR

This study used e-EVN observations to investigate a mysterious radio source suspected of being a dark gravitational lens, finding evidence of active galactic nucleus activity and ruling out lensing.

Contribution

First high-resolution radio observations of a suspected dark lens, providing insights into its nature and ruling out gravitational lensing as the cause of observed radio features.

Findings

Detected strong AGN activity in the source

Ruled out the source being a gravitational lens

Provided high-resolution imaging of the suspected dark lens

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.