Gamma-ray
photons(光子) seen
emanating1(放射) from the center of the
Milky2 Way
galaxy3 are consistent with the
intriguing4(有趣的) possibility that dark-matter particles are
annihilating5(消灭) each other in space, according to research submitted by UC Irvine astrophysicists to the American Physical Society journal Physical Review D. Kevork Abazajian, assistant professor, and Manoj Kaplinghat, associate professor, of the Department of Physics & Astronomy
analyzed6 data collected between August 2008 and June 2012 from NASA's Fermi Gamma-ray Space Telescope orbiting Earth. They found more gamma-ray photons coming from the Milky Way galactic center than they had expected, based on previous scientific models. Gamma-rays are electromagnetic radiation emitted during radioactive decay or other high-energy particle processes.
"This is the first time this new source has been observed with such high
statistical7 significance, and the most striking part is how the shape,
spectrum8 and rate of the observed gamma rays are very consistent with the leading theories for dark matter," Abazajian said. "Future observations of regions with less
astrophysical(天体物理学的) emission9, such as
dwarf10 galaxies11, will be able to
conclusively12 determine if this is actually from the dark matter."
Nonluminous and not directly
detectable13, dark matter is thought to account for 85 percent of the universe's mass. Its existence can only be inferred from its gravitational effects on other, visible matter. The UCI researchers' findings could support its presumed presence at the center of galaxies.
The
prevailing14 hypothesis is that dark matter is composed of weakly interacting massive particles, or
WIMPs16. When two WIMPs meet, they
annihilate17 each other to produce more familiar particles -- including gamma rays.
Although the data
interpretation18 seems to be consistent with dark-matter theory, the gamma rays could be coming from a source other than
WIMP15 destruction, Kaplinghat
noted19. "The signal we see is also consistent with photons emitted by pulsars," he said, "or from high-energy particles
interacting(相互作用) with gas in the galactic center."