Other common features in these collisions are quasars. These are believed to be super massive black holes at the centers of the colliding galaxies that give off powerful bursts of X-rays when they are feeding on matter. Some researchers suspect that collisions are the best time to see super massive black holes feeding because of all that gas and dust that's flying helter-skelter during the cosmic dance. Even our Milky Way is not immune. It has already gobbled up some smaller galaxies and is on a crash course with Andromeda. That dance ought to begin in about 2 billion years, say astronomers. In the end, all of the colliding spiral galaxies will form what are called elliptical galaxies -- which are more like colossal spheres of stars. These are thought to be the old-age homes for stars, since most of the gas and dust are used up in elliptical galaxies and few new stars form in them. "Every massive galaxy may not go through a 'major' merger such as those seen in most of the HST images, but every galaxy goes through at least a 'minor' merger," Evans told Discovery News. "By minor merger, I mean a merger of a massive galaxy like our own and a much less massive satellite galaxy like the Magellanic Clouds. These types of accretion events happen all of the time." Most of the collisions are part of a larger study of galaxies that are exceptionally bright in infrared light called the Great Observatories All-sky LIRG Survey. The survey brings together images from Hubble, NASA's infrared Spitzer Space Observatory, NASA's Chandra X-Ray Observatory and NASA's Galaxy Explorer. Related Links: Larry O'Hanlon's blog: Earth Impacts |
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