Could a Primordial Black Hole Explosion Explain the extremely high-energy KM3NeT neutrino Event?

Abstract

A black hole is expected to end its lifetime in a cataclysmic runaway burst of Hawking radiation, emitting all Standard Model particles with ultra-high energies. Thus, the explosion of a nearby primordial black hole (PBH) has been proposed as a possible explanation for the $\sim 220$~PeV neutrino-like event recently reported by the KM3NeT collaboration. If the event originated from a PBH, the source would need to lie at $(1-7)\times 10^{-5} \mathrm{pc}$ - depending on the assumed effective area - thus within the Solar System. At such proximity, the resulting flux of gamma rays and cosmic rays would be detectable at Earth. By incorporating the time-dependent field of view of gamma-ray observatories, we show that LHAASO should have recorded $\mathcal{O}(10^8)$ events between fourteen and seven hours prior to the KM3NeT detection. IceCube and KM3NeT \textit{itself} should likewise have detected of order a few hundred events in the range $1~\mathrm{TeV} \lesssim E_ν\lesssim 1~\mathrm{PeV}$ during the 24 hours preceding the burst. The absence of any such multi-messenger signal, particularly in gamma-ray data, strongly disfavors the interpretation of the KM3-230213A event as arising from evaporation in a minimal four-dimensional Schwarzschild scenario.

Figures (3)

• Figure 1: Time integrated Hawking spectrum times energy-squared for three different time intervals: $\Delta t =$ 1 day to 1 minute (dotted lines), 1 minute to $10^{-3}$ ms (dashed lines), and $10^{-3}$ ms to 0 s (solid lines) before complete evaporation, assuming a PBH located at a distance of $2.4\times 10^{-5}$ pc from Earth. We consider the spectra of neutrinos (red), electrons and positrons (yellow), muons (green), photons (blue), and protons (dark blue). The purple band indicates the energy range associated to the KM3-230213A event at 90% CL.
• Figure 2: Field of view in equatorial coordinates covered by gamma-ray experiments HAWC historical:2023opoHAWC:2019wla (purple) and LHAASO DiSciascio:2016rgiLHAASO:2019qtb (light green), together with the regionswhere the effective areas of KM3NeT (orange) and IceCube (light blue) are $25\%$ below their maximum value for an energy equal to the measured by KM3NeT. The colored regions denote the instantaneous field of view of these experiments at the time of the KM3NeT event, 13th of February 2023 at 01:16:47 UTC KM3NeT:2025npi (red star). The area encompassed by the dashed lines represent the corresponding regions nine hours earlier.
• Figure 3: Expected number of events at Earth during the final day before the evaporation of a PBH located at the KM3-230213A sky position, assuming a distance of $2.4\times10^{-5}$ pc. Shown are photon (green) and proton (brown) counts in LHAASO, HAWC photons (lilac dashed), and neutrino events in IceCube (light blue) and KM3NeT for $E_\nu \in [1~\mathrm{TeV}, 1~\mathrm{PeV}]$ (dark blue) and $E_\nu \in [1~\mathrm{PeV}, 1~\mathrm{EeV}]$ (red). Bands reflect events obtained when varying the PBH distance from $10^{-5}$ to $7\times10^{-5}$ pc.