Friday, September 07, 2007
Scientists discover (very) big hole in universe
New Scientist reports: [edited]
Radio astronomers have found the biggest hole ever seen in the universe. The void, which is nearly a billion light years across, is empty of both normal matter and dark matter. The finding challenges theories of large-scale structure formation in the universe.
Lawrence Rudnick and colleagues of the University of Minnesota in Minneapolis, US, stumbled upon the void by accident. Rudnick’s team had been studying data from a survey carried out by the Very Large Array radio telescope in New Mexico, also in the US. "One morning I was a little bored, and said, 'why don’t I look in the direction of the WMAP cold spot’," says Rudnick.
The team was in for a surprise. They saw little or no radio sources in a volume that is about 280 megaparsecs or nearly a billion light years in diameter. The lack of radio sources means that there are no galaxies or clusters in that volume, and the fact that the CMB is cold there suggests the region lacks dark matter, too.