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Quasars have the distinction of being the brightest objects in the universe. As such, scientists surmised that they were most likely born out of large and tumultuous galaxies. But new findings from an international collaboration suggest that quasars can arise in humdrum galaxies much less intense than the Milky Way. "It¿s like finding a Formula One racing car in a suburban garage," notes team leader Scott Croom of the Anglo-Australian Observatory.
Using the Frederick C. Gillett Gemini North Telescope in Hawaii, astronomers studied nine galaxies, located about 10 billion light-years away from the earth, that host quasars. (The image above, of a quasar known as PKS 0637-72, was obtained using the Chandra X-ray Observatory.) "We¿d hoped their sizes and shapes might give clues as to what triggered quasar activity," Croom explains. But the researchers had trouble detecting the galaxies at all. Indeed, all but one were too faint or small to observe once the light from the quasar itself was accounted for.
Theory holds that quasars are powered by supermassive black holes that turn incoming matter into streams of radiation. Known supermassive black holes are associated with galaxies much larger than the ones analyzed in this study. Because the quasars examined in the new work formed when the universe was just four billion years old, they provide insight into how galaxies and black holes formed and evolved in the early universe. Notes team member David Schade of the Dominion Astrophysical Observatory in Victoria, B.C., "This finding is particularly exciting because it means that we may need to rethink our models of how quasars work." The results of this study were presented yesterday at the Gemini Science conference in Vancouver.