The earth is constantly barraged by cosmic rays, but scientists have noticed an unusually large amount of high-energy positrons – the antimatter counterparts of electrons. Now a group of researchers from the United States, Mexico, Germany, and Poland might have an explanation. According to the Institute of Nuclear Physics Polish Academy of Sciences (IFJ PAN), the excess positrons might be “the first particles recorded by humans to be derived from the interaction of dark matter.”

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In 2008, a probe in our planet’s orbit detected more positrons reaching us than scientists would anticipate. So a large team conducted observations at the recently activated High-Altitude Water Cherenkov Gamma-Ray Observatory in Mexico to see if pulsars were the source of these baffling extra positrons. They analyzed data from two relatively close pulsars around 800 and 900 light years away. These pulsars, Geminga and PSR B0656+14, are “among the strongest sources of cosmic rays in our region of the galaxy,” according to IFJ PAN.

Related: Scientists observe light spectrum of antimatter for the first time ever

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The pulsars, albeit responsible for some of the positrons, contributed too small an amount to account for all the antimatter hitting Earth. Instead, the researchers’ observations bolstered a competing hypothesis IFJ PAN described as much more exotic: the “annihilation or decay or dark matter” could be the origin of the positrons. If the hypothesis is correct – and we won’t know for sure until future observations back it up or not – these perplexing positrons would be the first particles we’ve ever recorded coming from the interaction of dark matter.

The journal Science recently published the research. The University of Utah led the international team.

Via the Institute of Nuclear Physics Polish Academy of Sciences and ScienceAlert

Images via John Pretz/IFJ PAN and Jordan A. Goodman/IFJ PAN