spacetoday.net: Hubble detects ring of dark matter

Posted: Wed, May 16, 2007, 7:44 AM ET (1144 GMT)
Hubble image of dark matter ring (NASA, ESA, M.J. Jee and H. Ford (Johns Hopkins University))

Astronomers announced Tuesday that they have discovered a ring of dark matter created by the collision of two massive galaxy clusters. The ring, located in a galaxy cluster, CL0024+17, five billion light-years away, is about 2.6 million light-years across. Astronomers detected the ring indirectly by mapping the gravitational bending of light from most distant galaxies caused by the cluster. The ring may have been created by the collision of that galaxy cluster with another one to two billion years ago. Because the ring is not directly associated with the galaxies and hot gas found in the cluster, astronomers consider the ring's discovery the strongest evidence to date for the existence of dark matter, which does not otherwise interact with ordinary matter or light.