Extended Gas in Active Galaxies
These Hubble Space Telescope images reveal a set of bizarre, greenish, looping, spiral, and braided shapes around eight active galaxies. These huge knots of dust and gas appear greenish because they are glowing predominately in light from photoionized oxygen atoms.Each galaxy hosts a bright quasar that may have illuminated the structures. The ethereal wisps outside the host galaxies were blasted, perhaps briefly, by powerful ultraviolet radiation from a supermassive black hole at the core of each galaxy. Material falling into the black hole was heated to a point where a brilliant searchlight beam traveled into deep space. Because the quasars are not bright enough now to account for the present glow of the blobs, they may be a record of something that happened in the past inside the host galaxies. The black holes may have been fueled through collisions between two galaxies, and the filaments may be forensic evidence for material tattered in the collision.