Hubble finds ring of dark matter

BALTIMORE, May 15 (UPI) -- The Hubble Space Telescope has found a "ghostly" ring of dark matter that formed long ago during a titanic collision between two galaxy clusters.

The discovery is said to be among the strongest evidence yet that dark matter exists.

Although astronomers do not know what composes dark matter, they hypothesize it is a type of elementary particle that pervades the universe.

"This is the first time we have detected dark matter as having a unique structure that is different from both the gas and the galaxies in the cluster," said astronomer M. James Jee of Johns Hopkins University. Jee is a member of the team that spotted the dark matter ring.

The ring, measuring 2.6 million light-years across, was found in the cluster CL0024+17, 5 billion light-years from Earth.

Said Jee: "I was annoyed when I saw the ring because I thought it was an artifact, which would have implied a flaw in our data reduction. I couldn't believe my result. It took more than a year to convince myself that the ring was real."

A paper on the discovery is to be published in the June 1 issue of the Astrophysical Journal.