‘Galaxies and Massive Black Holes’

Evidence has been accumulating for several decades that many galaxies harbor central mass concentrations that may be in the form of black holes with masses between a few million to a few billion time the mass of the Sun. This lecture presents measurements over the last two decades employing adaptive optics imaging and spectroscopy on large ground-based telescopes which prove, beyond reasonable doubt, that such a massive black hole exists in the center of our Milky Way. Most recently, a tidally disrupting cloud of gas has been discovered on an almost radial orbit that reached its peri-distance of 2000 Schwarzschild radii in 2014, promising a valuable tool for exploring the innermost accretion zone. Future interferometric studies of the Galactic Center black hole will foreseeably be able to test gravity in its strong field limit.