Swift is a NASA satellite designed to spot gamma-ray bursts, the most powerful explosions in the Universe. They are named for the extremely energetic gamma rays they emit. Swift can also detect high-energy, or "hard" X-rays, which have nearly the energy of gamma rays. Swift’s ongoing survey of hard X-rays in space is revealing details about the kinds of dynamic cosmic activity can release such high-energy wavelengths of light. What kinds?
Swift’s views reveal only a spot of bright light at the source of the X-rays. By comparing Swift’s X-ray sources to visible-light views of the same regions, scientists found that many of the high-energy X-ray emissions are positioned at the centers of colliding galaxies. Since supermassive black holes typically occupy galaxy centers, the research supports theories that the merger of matter in the galaxy centers can fuel black holes to spawn extraordinary flares of high-energy light, much more energy than is typically observed from the center of a single, non-colliding galaxy. The find has meaning for the future of the black hole at the center of our own Milky Way galaxy, which is destined to collide with the nearby Andromeda galaxy in approximately three billion years. The collision simulation in this Astro Bulletin was developed by AMNH astrophysicists and featured in the Space Show Cosmic Collisions.