| Description: | Gravitational lensing is a powerful tool for studying the mass content in distant galaxies, but also for performing detailed studies of high-redshift sources. In this talk I will present milliarcsecond angular resolution observations of radio-loud gravitationally lensed sources, which have been used to investigate the properties of both foreground lensing galaxies and background sources. From the analysis of high angular resolution observations with the global Very Long Baseline Interferometric (VLBI) array of the gravitational extended radio arcs in MG J0751+2716 (at z = 3.2), we were able to determine the inner (baryonic and dark matter) mass profile of a group of galaxies and investigate the smoothness of the mass density distribution on mas-scales. By comparing two VLBI observations at milliarcsecond angular resolution separated by ~14 years, we found evidence for proper motions in the gravitationally lensed source MG B2016+112 at z = 3.273. This is the first time that proper motions have been clearly detected in a gravitational lensing system. The observed proper motions combined with multi-band observations of this source are consistent with both a gravitationally lensed single AGN and a dual AGN system. Finally, I will present the results from a new pilot gravitational lens search in the VLBI survey mJIVE-20 in perspective of future surveys with the current and next generation of radio interferometers. |
