Jets in AGN – New Results from HST and VLA

This paper summarizes some of our recent projects which try to illuminate the nature and importance of jets associated with active nuclei and compact objects. After a short introduction on jets in radio galaxies and radio loud quasars the paper focuses on jets in other source types, such as radio-quiet quasars, Seyfert and LINER galaxies, and stellar mass black holes. Radio observations of quasars, for example, have brought new evidence for the existence of relativistic jets in radio quiet quasars, while HST and VLA observations of Seyfert galaxies have now clearly established not only the presence of radio jets, but also the great importance these jets have for the morphology and the excitation of the emission line region in these AGN. Moreover, a recent VLA survey found a large fraction of low-luminosity AGN to host compact, flat-spectrum radio cores indicating the presence of radio jets there as well. Finally the jet/disk-symbiosis model, which successfully explains radio cores in LINER galaxies, is applied to the stellar mass black hole GRS 1915+105, indicating that the radio cores in both types of sources are just different sides of the same coin. The conclusion drawn from all these observations is that radio jets are a ubiquitous feature of most—if not all—AGN and play an important effect in the overall energy budget, as well as for the interpretation of observations in other wavebands (e.g. optical emission lines).