University of California-Santa Cruz Professor Piero Madau said previous simulations showed the Milky Way clear of dark matter but the new study utilizing the Jaguar supercomputer at Oak Ridge National Laboratory provided enough detail to see clumps of dark matter.

So far, dark matter has been detected only through its gravitational effects on stars and galaxies, the researchers said. But one theory posits dark matter consists of weakly interacting massive particles that emit gamma rays when they collide.

Madau said gamma rays from such collisions might be detectable by the recently launched Gamma-ray Large Area Space Telescope.

"That's what makes this exciting," he said. "Some of those clumps are so dense they will emit a lot of gamma rays if there is dark matter annihilation and it might easily be detected by GLAST."

In a separate paper to appear in the Astrophysical Journal, the researchers make specific predictions about the gamma-ray signals that would be detectable by GLAST.

The new study that included postdoctoral fellow Juerg Diemand is detailed in the journal Nature.