At the heart of the more massive galaxies in the universe, there are supermassive black holes (SMBHs) so powerful that they outshine all of the stars in their galactic disks. The core regions of these galaxies are known as active galactic nuclei (AGN), or by their more popular moniker “quasars.” The ongoing study of these objects provides a testbed for general relativity and reveals a great deal about the formation and evolution of galaxies and the large-scale structure of the universe.
