Primordial Black Holes and Neutrinos: KM3NeT’s Unexpected Cosmic Insights

In 2023, the KM3NeT detector, located at the bottom of the Mediterranean Sea, recorded a neutrino with an energy of 220 PeV, becoming one of the most energetically powerful particles ever registered. For comparison, the energy of this particle is a billion times greater than that of an ordinary solar neutrino and significantly exceeds what the Large Hadron Collider can create. The event, named KM3-230213A, surprised scientists: known astrophysical sources, such as supernovae, gamma-ray bursts, or active galactic nuclei, cannot explain the appearance of such high-energy neutrinos.

Recent work in Physical Review Letters offers a novel explanation: the neutrino source could be primordial black holes (PBH)-hypothetical objects formed immediately after the Big Bang from dense clusters of elementary matter. Unlike ordinary black holes, PBHs can evaporate via Hawking radiation, gradually losing mass and becoming hotter until they explode in a final phase.

Scientists suggest that during this last burst, PBHs emit neutrinos and other subatomic particles with extreme energy. The model considers a special type of PBH with a “dark charge”-a particle analogous to an electron but with high mass, which explains why IceCube did not detect similar neutrinos: its sensitivity is limited to 10 PeV.

According to the model, such explosions may occur approximately once a decade. At the moment of final PBH decay, particles are released, both known (electrons, quarks) and hypothetical or not yet discovered, creating a unique spectrum of cosmic radiation. For researchers, KM3-230213A may serve as indirect evidence of PBH existence and their interaction with dark matter.

The “dark charge” model makes predictions more accurate because it accounts for the behavior of PBHs in an extreme state, nearly reaching the maximum charge-to-mass ratio. The authors emphasize that the discovery not only resolves the mystery of the ultra-high-energy neutrino but also opens new possibilities for studying rare cosmic processes that cannot be recreated on Earth.

“Our model is more complex than others, but it is precisely this complexity that allows us to explain a phenomenon that otherwise remains unexplained,” notes Michael Baker, lead author of the study. The KM3-230213A event and its interpretation could become a significant step in understanding the nature of primordial black holes, mechanisms of evaporation, and the origins of high-energy cosmic particles, linking fundamental physics with observational astrophysics.