Researchers go looking for ordinary matter of the cosmic web

GENEVA, Switzerland, Dec. 3 (UPI) -- In a recent study, researchers at the University of Geneva, in Switzerland, set out to to locate the universe's missing ordinary matter. They may have found it -- some of it, at least.

Ordinary matter makes up only 5 percent of the universe. But scientists have yet to locate it all. The matter yet to be found is referred to as the "missing baryons," and researchers believe it's strung along in filaments of hot gas that make up the cosmic web.

These strands link up and form knots, where hot gas cools and condenses to form star-forming galaxies.

Because cosmologists believe these filaments dictate the formation of galaxies -- finding and understanding the missing baryons is essential to understanding the formation of the universe.

To locate the missing matter, scientists decided to take a closer look at Abell 2744, a massive cluster of galaxies. In the middle of the cluster, researchers had detected an intricate mixing of dark and luminous matter.

The closer look was bolstered by the XMM space telescope, which is extra sensitive to X-rays and therefore able to detect very hot gas.

When scientists pointed XMM at places where they expected to find filaments of the cosmic web, the telescope picked up evidence of super hot gas -- 10-million degree hot gas structures.

The findings, detailed in the journal Nature, correspond with the numbers spit out by cosmic web models.

"Now we must verify that the discovery of Abell 2744's missing baryons is applicable to the entire universe," Dominique Eckert, lead scientist, said in a press release. "This will consist in studying these filamentary regions in detail, and measuring their temperature distribution and the various atoms that compose them, in order to understand how many heavy elements there are in the universe."