‘Unattainable’ particle that hit Earth might have been darkish matter

A particularly high-energy particle that was noticed tearing by Earth has left scientists flummoxed ever because it was found. Whereas many researchers imagine the particle was an uncommon neutrino, some are actually suggesting it might be one thing even wilder: a particle of darkish matter travelling throughout the cosmos.

The KM3NeT detector, off the coast of Italy, noticed this “not possible” neutrino in 2023 whereas it was nonetheless below building. The particle in query was of immense proportions, 35 occasions extra energetic than any seen earlier than. The place it got here from stays a thriller, with attainable sources together with a galaxy with a really lively central black gap often called a blazar, or a background supply of high-energy neutrinos pervading the universe.

Bhupal Dev at Washington College in St. Louis, Missouri, and his colleagues have one other thought. They recommend the occasion won’t have been a neutrino in any respect, however as an alternative a darkish matter particle crashing into our planet that originated from a blazar. “It opens up a brand new approach you may actually take a look at darkish matter,” he says. “We will convert these neutrino telescopes into darkish matter detectors.”

Neutrino detectors have already got a troublesome job to do as a result of these particles are extraordinarily tiny and almost massless, hardly ever interacting with matter as they traverse the cosmos. Once they arrive at Earth, they’ll sometimes crash into atoms, producing a particle known as a muon that may be picked up by neutrino detectors like KM3NeT and IceCube on the south pole.

IceCube has seen proof for a whole lot of cosmic neutrinos since 2011, however by no means one thing as energetic as KM3NeT’s discovery. That was complicated, as a result of no matter supply KM3NeT was seeing, IceCube ought to have seen it too.

Dev says that if the incoming particle was darkish matter and never a neutrino, it might clarify this thriller. The shallow predicted path of the incoming particle meant that it needed to journey by extra of Earth to achieve KM3NeT than IceCube, rising the prospect of it being scattered right into a muon. “The darkish matter goes by a lot of Earth’s matter,” says Dev, “and we will clarify why IceCube didn’t see it.”

The particle would have been produced in a blazar after which fired in direction of Earth in a beam. Dev favours this concept as a result of high-energy protons in a blazar extra effectively switch their power into darkish matter than neutrinos, he says. The overwhelming majority of the opposite occasions detected by KM3NeT and IceCube would in all probability nonetheless have been neutrinos.

Not everyone seems to be satisfied simply but. “From an Occam’s razor perspective, that is in all probability simply an odd neutrino that’s distinctive in power,” says Dan Hooper on the College of Wisconsin–Madison. Nonetheless, if appropriate, it could give us a way to search out and examine darkish matter particles, which have by no means beforehand been detected. “Everyone could be fairly thrilled if these machines can examine not solely neutrinos but additionally darkish matter,” says Hooper.

Shirley Li on the College of California, Irvine, says the thought might be examined in future, as any incoming darkish matter particle ought to produce two muons within the detector when it hits Earth, not only one, however the detectors presently lack the precision to tell apart two particles from a single sign. “That’s doubtlessly testable, however at these energies muon reconstruction may be very troublesome,” she says.