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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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ScienceShot: Black Holes Tease Out a Dark Matter Secret
23 March 2010 1:04 pm
The mysterious substance known as dark matter—which makes up six times more of the universe than ordinary, visible matter—may have finally yielded one of its secrets. Astronomers studying the behavior of supermassive black holes, the gigantic beasts lurking at the hearts of most galaxies, have discovered that dark matter seems to have a density limit. As a supermassive black hole sucks in material from the surrounding galaxy, part of that material is dark matter, which is invisible except for its gravitational pull. Astronomers know that galaxies need the extra gravity from dark matter to keep their constituent stars from flying off into space. But if too much dark matter got pulled into supermassive black holes, there wouldn't be enough to hold galaxies together. Researchers calculate in an upcoming issue of the Monthly Notices of the Royal Astronomical Society, that the maximum density for dark matter must be seven times the mass of the sun per cubic light-year of space. Any more than that amount, and supermassive black holes would have grown so large that they would have devoured giant swaths of material from the hearts of galaxies, possibly obliterating them entirely.