When worlds collide

Astronomers believe the a mega-merger in the galaxy known as Arp 220 triggered the formation of huge numbers of new stars, sent shock waves rumbling through intergalactic space, and could possibly lead to the formation of a supermassive black hole in the center of the new conglomerate galaxy. Data collected by the Chandra X-ray observatory also suggest that merger of these two galaxies began only 10 million years ago, a short time in astronomical terms. Scientists are interested in such head-on collisions between galaxies because all galaxies -- including our own -- may have undergone mergers. The research provides insight into how the Universe came to look as it does today. "The unusual concentration of X-ray sources in the very center of Arp 220 suggests that we could be observing the early stages of the creation of a supermassive black hole and the eventual rise to power of an active galactic nucleus," said Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics, a member of the team studying Arp 220.