Mysterious Dark Matter Might Actually Glow

The strange stuff makes up about 85 percent of the heft of the universe. It's invisible, but researchers know it's there because there is not enough regular matter -- stars and planets and gas and dust -- to hold galaxies and galaxy clusters together. Some other unseen material, dubbed dark matter, must be gluing things together.

So how to find that which you cannot see?

A new computer simulation of the evolution of a galaxy like our Milky Way suggests it might be possible to observe high-energy gamma-rays given off by dark matter.

"These calculations finally allow us to 'see' what the dark matter distribution should look like near the Sun where we might stand a chance of detecting it," said Simon White, director of the Max Planck Institute for Astrophysics.

White is part of the international Virgo Consortium, a team of scientists including cosmologists at Durham University. Their findings are detailed in the Nov. 6 issue of the journal Nature.

Past studies have indicated that dark matter was crucial in the formation of galaxies, and that the mystery material still hangs around in halos that surround galaxies. The new simulation examined how these dark matter halos might evolve and behave.

The virtual galaxy's halo grew through a series of violent collisions and mergers between much smaller clumps of dark matter that emerged from the Big Bang, the theoretical beginning of the universe. The simulation revealed that gamma-rays produced when particles collided in areas of high dark matter density could be most easily detectable in regions of the Milky Way lying close to the sun -- in the general direction of the galaxy's center.

The scientists figure that NASA's Fermi Telescope should search in this part of the galaxy for a signature glow of dark matter.

"The search for dark matter has dominated cosmology for many decades," said Carlos Frenk, director of the Institute for Computational Cosmology at Durham University. "It may soon come to an end."

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