GRAVITY: the first two years harvest
Dr. Paulo Garcia
CENTRA/University of Porto/ESO
GRAVITY is the 4-beam K-band recombiner of the Very Large Telescope Interferometer. Some of the scientific results of the first two years of the GRAVITY consortium observations will be presented. These results are not only scientific breakthroughs but represent a revolution in infrared long baseline interferometry. Because expertise in this technique is not very widespread the presentation will be very pedagogical. The talk will focus on only some key results based on their scientific impact and illustration of interferometric techniques. We start by presenting the power of the differential phase to conduct spectroastrometric studies at tens of micro-arcseconds and how it allowed to resolve the broad line region of the quasar 3C 273 and the jets of the micro-quasar SS 433. We then proceed by presenting imaging results of the wind of eta Carina. Moving to young stars we show how orbits of close binaries, planet forming disks and its winds can be probed with visibility information. Then the capacity of GRAVITY in obtaining spectra of extrasolar planets is shown. We then present phase referenced imaging of SgrA*, tracking the movement of S2 through periastron passage, resulting in the detection of its gravitational redshift. The astrometry in the infrared with Gaia-like precision of SgrA* flares is shown to probe circular motion near the last stable orbit of the supermassive black hole. The talk ends with some thoughts for the future.