Abstract

One of the most exciting opportunities offered by the new VLT beam combiner GRAVITY is to directly resolve the immediate regions around the super-massive black holes (SMBHs) in the centres of active galaxies (AGN), i.e. the Broad Line Region (BLR) and the hot dust (“torus”) structures. We are exploiting this capability to study the inner workings of AGN in the K-band on unprecedented micro-arcsecond (sub-pc) spatial scales. This has led to the first interferometric detection of a BLR (finding ordered rotation and measuring the black hole mass in the quasar 3C273), as well as to the first 0.2 parsec resolution K-band image of the dust sublimation region in the nucleus of the Seyfert 2 galaxy NGC1068 (finding a ring-like structure which is inconsistent with the expected signatures of a geometrically and optically thick torus). I will summarize these and other recent results, discuss their scientific (and historical) context, and give an outlook how such observations (along with already planned or potential future upgrades of GRAVITY ) might contribute to the study of the structures and physical processes around SMB Hs or to the study of how SMB Hs build up their mass across cosmic time.