By Ron Cowen
For years, most claims that scientists had found evidence of dark matter, the ghostly material believed to account for more than 80 percent of the universe’s mass, have seemed to dissolve into thin air. But a new claim of dark matter detection may have more than a dollop of cosmic credibility, scientists say.
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Physicists Dan Hooper of the Fermi National Accelerator Laboratory in Batavia, Ill., and the University of Chicago and Lisa Goodenough of New York University base their findings, posted October 15 at arXiv.org, on an unexplained excess of energetic gamma rays emitted from the core of the galaxy. The gamma rays were recorded over the past two years with an instrument aboard NASA’s Fermi Gamma-ray Space Telescope, launched in 2008.
Dark matter, like ordinary atomic matter, is expected to concentrate at the galaxy’s center. That makes the Milky Way’s crowded core one of the most promising places to look for signs of the dark stuff, theorists agree. It’s also one of the most complex places to search, because the core is riddled with a variety of ordinary but poorly understood sources of gamma ray emission, notes Fermi scientist Steve Ritz of the University of California, Santa Cruz.