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6 March 2014 1:04 pm ,
Vol. 343 ,
Magdalena Koziol, a former postdoc at Yale University, was the victim of scientific sabotage. Now, she is suing the...
Antiretroviral drugs can protect people from becoming infected by HIV. But so-called pre-exposure prophylaxis, or PrEP...
Two studies show that eating a diet low in protein and high in carbohydrates is linked to a longer, healthier life, and...
Considered an icon of conservation science, researchers at World Wildlife Fund (WWF) headquarters in Washington, D.C.,...
The new atlas, which shows the distribution of important trace metals and other substances, is the first product of...
Early in April, the first of a fleet of environmental monitoring satellites will lift off from Europe's spaceport in...
Since 2000, U.S. government health research agencies have spent almost $1 billion on an effort to churn out thousands...
- 6 March 2014 1:04 pm , Vol. 343 , #6175
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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.