20070108

Mapping dark matter

"An international team of astronomers using NASA's Hubble Space Telescope has created a three-dimensional map that provides the first direct look at the large-scale distribution of dark matter in the universe.

"This new map provides the best evidence to date that normal matter, largely in the form of galaxies, accumulates along the densest concentrations of dark matter. The map reveals a loose network of filaments that grew over time and intersect in massive structures at the locations of clusters of galaxies.

"The map stretches halfway back to the beginning of the universe and shows how dark matter has grown increasingly 'clumpy' as it collapses under gravity.

"Mapping dark matter's distribution in space and time is fundamental to understanding how galaxies grew and clustered over billions of years. Tracing the growth of clustering in dark matter may eventually also shed light on dark energy, a repulsive form of gravity that would have influenced how dark matter clumps.

"The research results appeared online today in the journal Nature and were presented at the 209th meeting of the American Astronomical Society in Seattle by Richard Massey and Nick Scoville. Both researchers are from the California Institute of Technology in Pasadena, California."