Science NOW - 2010 Feb 17
Physicists may not know what dark matter is, but they're getting a better idea of what it's not. Data from NASA's orbiting Fermi Gamma-ray Space Telescope puts a crimp in particle theorists' favored explanation of the mysterious stuff whose gravity holds the galaxies together, ruling out a hefty range of masses for the hypothesized particles, a team announced this week. Curiously, the result comes not from the Fermi team itself, but from other particle astrophysicists who analyzed the Fermi data.