Supermassive black holes are among the most exciting and puzzling objects in the universe. These are the giant, massive bodies that sit at the heart of most, perhaps all, galaxies. Indeed, they may be the seeds from which all galaxies grow.
Supermassive black holes are at least a hundred thousand times the mass of our sun. They are often surrounded by thick clouds of gas that radiate vast amounts of energy. When this happens, they are called active galactic nuclei. Discovering the properties of these clouds, and their curious central residents, is an ongoing exercise for astrophysicists.
