Περίληψη :
In this talk I will present the state-of-the art and future perspectives of observations of active galactic nuclei (AGN) with high-resolution very-long-baseline interferometry (VLBI). This technology enables the observation of the central acceleration and collimation zone of parsec-scale jets in AGN. A lot of open questions remain on how these jets are formed, and via which mechanisms particles are accelerated and the jets collimated up to kiloparsec-scale distances. To address these questions, I will highlight results from both the latest space-borne VLBI mission RadioAstron, as well as short-wavelength observations culminating in the latest efforts of the event horizon telescope (EHT) collaboration. I will also discuss a new project to determine magnetic field profiles along AGN jets with high-frequency phase-referencing observations, which could put some constrains on the nature of the jet launching region.
