Posted by news on February 07, 2005 at 02:19:11:
Scientists find some of universe's missing matter
Scientists find some of universe's missing matter
Thu Feb 3, 8:47 AM ET
PARIS (AFP) - Some of the universe's missing "normal" matter has been found hiding in clouds of hot gas between galaxies, according to research published in the British scientific journal Nature.
Just five percent of the universe is believed to be made up of "normal" matter such as atoms and molecules, but scientists have only be able to find about half the expected amount.
Fabrizio Nicastro of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and his colleagues looked at X-rays from a distant quasar called Markarian 421 as they passed through a region of warm gas.
The X-rays were absorbed by ionized oxygen and nitrogen atoms there that are normally "invisible," and the scientists say there is enough matter in the gas to account for the missing mass.
"It is difficult to know whether this region is typical of the entire universe," said Michael Shull of the University of Colorado in a separate commentary in this week's Nature.
"Unfortunately, most other quasars are not bright enough to provide such high-quality data."
Scientific models predict that 95 percent of the universe is composed of dark matter and energy, the effects of which can be discerned from the gravitational motion of stars and galaxies.
A quasar is a star-like body that may send out radio waves and other forms of energy.