Some galaxies have centers that are hundreds of times brighter than normal galaxies. These central regions are called active galactic nuclei (AGN); the most energetic and distant AGNs in the universe are known as quasars. AGNs are powered by material accreting onto massive black holes, which are so powerful that nothing, not even light, can escape their grasp. Astronomers once thought that black holes were fairly rare. But Carnegie astronomers, with collaborators, found instead that supermassive black holes actually lie at the center of all massive galaxies studied to date. It also turns out that the mass of the black hole is closely related to the properties of the host galaxy and is intricately involved in galaxy formation. Image courtesy NASA