The Fermi Space Telescope has detected 1,873 gamma ray sources in space, and nearly 600 are complete mysteries, NASA wrote today on its website.
NASA's Fermi team has recently released the second catalog of gamma ray sources from its satellite's Large Area Telescope and have no idea where nearly one-third of gamma rays originated.
"Fermi sees gamma rays coming from directions in the sky where there are no obvious objects likely to produce gamma rays," said David Thompson, Fermi deputy project scientist, of Goddard Space Flight Center in Maryland.
Gamma rays are a "super-energetic form of light produced by sources such as black holes and massive exploding stars," according to NASA.
Researchers say two-thirds of the gamma rays come from objects such as pulsars or blazars. The remaining third are a complete mystery right now.
Researchers are speculating on the nature of the mystery sources, including the possibility that they are made of dark matter.
"Some of the mystery sources could be clouds of dark matter, something that's never been seen before," Thompson said.
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