New evidence claimed for dark matter

Posted by Emma Woollacott

Physicists say they've found more evidence for the existence of dark matter, in the form of gamma rays emanating from the center of the galaxy.

In an analysis of data collected between August 2008 and June 2012 from NASA's Fermi Gamma-ray Space Telescope, they've found more gamma-ray photons coming from the Milky Way galactic center than predicted by previous scientific models.

"This is the first time this new source has been observed with such high statistical significance, and the most striking part is how the shape, spectrum and rate of the observed gamma rays are very consistent with the leading theories for dark matter," says assistant professor Kevork Abazajian of UC Irvine.

"Future observations of regions with less astrophysical emission, such as dwarf galaxies, will be able to conclusively determine if this is actually from the dark matter."

Dark matter's believed to account for 85 percent of the universe's mass. It's theorized to consist of weakly interacting massive particles, or WIMPs. When two WIMPs meet, they annihilate each other to produce more familiar particles - including gamma rays.

Last week, Swiss astronomers claimed they'd identified large amounts of dark matter near our sun. However, other studies have appeared to cast doubt on its existence.

And while the new data is consistent with dark-matter theory, this isn't the only explanation.

"The signal we see is also consistent with photons emitted by pulsars, or from high-energy particles interacting with gas in the galactic center," says associate professor Manoj Kaplinghat.