Galaxies could yield dark matter clues

Nov. 8, 2011 at 5:46 PM
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ANN ARBOR, Mich., Nov. 8 (UPI) -- Two newly discovered dwarf galaxies outside the Milky Way could help reveal the nature of dark matter, U.S. astronomers say.

Researchers at the University of Michigan said the dwarf galaxies appear to be satellites of Andromeda, the closest spiral galaxy to Earth.

The astronomers searched for dwarf galaxies around Andromeda to help them understand how matter relates to dark matter, an invisible substance that neither emits nor reflects light, but is believed to make up most of the universe's mass and may be responsible for organizing visible matter into galaxies.

"These faint, dwarf, relatively nearby galaxies are a real battleground in trying to understand how dark matter acts at small scales," astronomy professor Eric Bell said in a university release Tuesday.

Current theories suggest visible galaxies are all nestled in beds of dark matter, with each bed, or halo, of dark matter having one galaxy in it.

The predictions match observations of large galaxies for a given volume of the universe, astronomy doctoral student Colins Slater said, "but it seems to break down when we get to smaller galaxies."

The models predict far more dark matter halos than we observe galaxies. We don't know if it's because we're not seeing all of the galaxies or because our predictions are wrong."

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