Cosmologists map dark matter

Dark matter--that strange, nearly invisible mass that makes up about a quarter of the Universe--is now on the map.

Cosmologists at the California Institute of Technology, Pasadena, have pieced together the first three-dimensional map of dark matter from hundreds of slightly overlapping images collected from the Hubble Space Telescope's Cosmic Evolution Survey (COSMOS), according to Nature, which published the map this week.

Dark matter is not readily seen because it doesn't emit or reflect enough electromagnetic radiation. Rather, the presence of dark matter is inferred from its gravitational effects on visible matter, thanks to the bright features characteristic of visible material. According to the report, dark matter "forms a filamentous 'skeleton' upon which visible matter congregates, eventually producing stars." The newly produced map, which will give scientists a better way to study the mass, shows some clumps of dark matter unaccompanied by bright features--befuddling scientists. "There will need to be a lot of follow-up work before we really believe any individual discrepancies," Richard Massey, a team member at the Institute, said in the report.