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Record-breaking neutrino may be final burst of an evaporating black hole
An exceptionally energetic neutrino that hit Earth with an estimated 220 petaelectronvolts (PeV) — far above the previous 10 PeV record — might be the last gasp of an evaporating primordial black hole, according to a new theoretical study. The event, cataloged as KM3-230213A and observed by the KM3NeT/ARCA detector network, has challenged conventional source models for ultra-high-energy neutrinos and opened an intriguing possibility: that Hawking radiation from a dying black hole produced the particle.
KM3-230213A's extreme energy forces scientists to revisit rare or novel mechanisms for particle production. In the new analysis, physicists Alexandra Klipfel and David Kaiser (MIT) modeled the Hawking evaporation of small, primordial black holes (PBHs) and calculated the expected neutrino yield during the black hole's final moments. Their results show that a small PBH in its last nanosecond could emit an enormous number of neutrinos, including a measurable fraction in the PeV-to-hundreds-of-PeV range.
Scientific background: primordial black holes and Hawking radiation
Primordial black holes are hypothetical compact objects that could have formed from density fluctuations in the first second after the Big Bang. Unlike stellar black holes, PBHs may have very low masses — down to asteroid-scale or smaller — and would lose mass over time via Hawking radiation, a quantum process proposed by Stephen Hawking that causes black holes to emit particles and gradually evaporate. The smaller the black hole, the higher the characteristic energy of its final emissions; the ultimate evaporation can appear as a rapid burst of high-energy particles.
Visual impression of the ultra-high energy neutrino event observed in KM3NeT/ARCA. (KM3NeT)
Klipfel and Kaiser show that a PBH with an asteroid-scale mass could, in principle, emit roughly 10^21 (one sextillion) neutrinos in its final nanosecond — enough that one of those neutrinos could collide with Earth with the energies recorded in KM3-230213A, provided the explosion occurred relatively nearby on cosmic scales.
Detection distance and probability
For a neutrino with KM3-230213A's energy to reach Earth, the PBH explosion would need to occur within about 2,000 astronomical units (AU), roughly 3 percent of a light-year — a distance well inside the Solar System's Oort cloud. Under the scenario where a substantial fraction of dark matter consists of primordial black holes, the authors estimate a detection probability of just under 8 percent for at least one such nearby PBH evaporation producing an event like KM3-230213A. While not high, the probability is non-negligible and motivates targeted searches.
Detection context and implications for dark matter
KM3NeT/ARCA and other neutrino observatories are designed to capture rare, energetic neutrino interactions with detectors buried deep underwater or in ice. Neutrino astronomy links particle physics to astrophysics because neutrinos propagate largely unimpeded across cosmic distances and carry direct information about extreme processes at their sources.
If validated, the PBH-Hawking explanation for KM3-230213A would be transformative: it would provide the first observational evidence for Hawking radiation and support the idea that at least part of dark matter might be composed of primordial black holes. The authors also argue that less energetic PeV neutrino events could arise from more distant PBH evaporations, producing a background of high-energy neutrinos from PBHs across the galaxy and beyond.
The claim is ambitious and requires more observational corroboration. As David Kaiser notes, "An 8 percent chance is not terribly high, but it's well within the range for which we should take such chances seriously — all the more so because so far, no other explanation has been found that can account for both the unexplained very-high-energy neutrinos and the even more surprising ultra-high-energy neutrino event." Alexandra Klipfel adds that this scenario offers a concrete set of signals experiments can test going forward.
Expert Insight
Dr. Maya R. Singh, an astrophysicist specializing in high-energy particle astronomy, comments: "The possibility that a single nearby primordial black hole evaporation produced KM3-230213A is tantalizing because it connects several unsolved problems — neutrino origins, Hawking radiation, and dark matter — in a testable way. The next steps are straightforward: increase exposure with current detectors, cross-check with complementary observatories, and refine models of PBH populations and spatial distribution. Detection of correlated signals (for example, gamma rays or a statistical excess of PeV neutrinos) would strengthen the case significantly."
Conclusion
The hypothesis that an exploding primordial black hole produced KM3-230213A offers an elegant explanation that unites quantum black hole physics with neutrino astronomy and dark matter research. It remains a speculative but testable scenario. Upcoming neutrino observations, improved event statistics, and cross-disciplinary searches for transient high-energy phenomena will be critical to determine whether Hawking radiation has finally been seen or whether another, yet-undiscovered astrophysical engine produced the record-breaking neutrino.
Source: sciencealert
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