An artist's conception of a rapidly growing black hole, otherwise known as an active galactic nucleus (AGN), in the center of a galaxy. A disk of hot gas is flowing into a central black hole, and is surrounded by a large doughnut or torus of cooler gas and dust. Earlier in the history of the universe, galaxies in clusters of galaxies are thought to have contained a lot more gas than galaxies in clusters do today. This abundance of fuel should mean that the piranha-like black holes were able to thrive in young, distant clusters by growing much faster than their counterparts in nearby clusters. Chandra observations have confirmed this by showing, for the first time, that there are more AGN in younger, more distant galaxy clusters. This illustration also shows jets of high energy particles (white) that are propelled away from the vicinity of the black hole by intense electric and magnetic fields. These jets can heat the gas in galaxy clusters and significantly affect their structure.