Impossible Neutrino Detected on Earth May Come From an Exploding Primordial Black Hole

In 2023, astronomers detected an extremely energetic subatomic particle hitting Earth. The energy was so high that known cosmic events couldn't explain it. A team of researchers suggests this "impossible" neutrino might be debris from an exploding primordial black hole, a tiny black hole formed soon after the Big Bang. If true, this could provide the first evidence of Hawking radiation and clues about the nature of dark matter.

Primordial black holes and Hawking radiation

According to the new research, regular stellar black holes are produced by dead stars, but scientists have predicted that much smaller "primordial" black holes could have appeared from the first fraction of a second in the universe's history. These small black holes might emit "Hawking radiation" gradually, losing mass and getting hotter. As physicist Andrea Thamm, from the University of Massachusetts, says, "The lighter the black hole is, the hotter it should be," and that's just before "it goes boom!" This "boom" is an explosion that shoots objects into space, a temporary occurrence that might one day be measured.

The neutrino mystery and dark charge

A KM3NeT neutrino detector in the Mediterranean captured a cosmic neutrino in 2023 with an energy of approximately 100 Peta-electronvolts (PeV), which surpasses the LHC output by a factor of 100,000. The phenomenon remains unexplained by known astrophysical sources, although an exploding primordial black hole could provide a potential explanation. The IceCube detector at the South Pole failed to detect a similar occurrence to the one that took place at the Antarctic site. UMass researchers propose these primordial black holes carry a new "dark charge" which acts as a heavy version of electric charge, thus rendering them mostly undetectable by IceCube. The explosion of charged black holes would produce ultra-energetic neutrinos.