Five-Dimensional Black Holes May Explain High-Energy Neutrino Detection

Research suggests the neutrino event KM3-230213A correlates with the decay of five-dimensional primordial black holes. These larger, colder black holes evade typical Hawking evaporation constraints, potentially accounting for the observed neutrino signal while remaining consistent with existing IceCube data on dark matter decay.

The enigmatic nature of dark matter continues to challenge cosmological models, prompting investigation into a range of potential candidates. Recent analysis focuses on the possibility that primordial black holes (PBHs), formed in the early universe, contribute to the dark matter density. A new theoretical framework, detailed in a paper by Anchordoqui et al., proposes a scenario where five-dimensional PBHs, existing within theories incorporating extra spatial dimensions, could explain a high-energy neutrino event detected by the IceCube Neutrino Observatory. The research, led by Luis A. Anchordoqui (Lehman College, City University of New York; Graduate Center, City University of New York; American Museum of Natural History) in collaboration with Francis Halzen (Wisconsin IceCube Particle Astrophysics Center, University of Wisconsin) and Dieter Lüst (Max–Planck–Institut für Physik, Werner–Heisenberg–Institut; Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität München), explores how the Hawking evaporation of these PBHs might account for the observed neutrino signal, potentially circumventing existing constraints on PBH abundance. The paper, entitled ‘Neutrinos from Primordial Black Holes in Theories with Extra Dimensions’, presents a model where these five-dimensional PBHs offer a viable explanation for the KM3Net detection of a high-energy neutrino.

Five-Dimensional Primordial Black Holes and the KM3NeT Neutrino Event

A recent study proposes a connection between the energy scale predicted by ‘dark dimension’ scenarios and the high-energy neutrino detected by the KM3NeT collaboration on 23 February 2023 (designated KM3-230213A). Researchers suggest this correlation arises from the Hawking evaporation of five-dimensional (5D) primordial black holes (PBHs), potentially offering a solution to outstanding problems in dark matter research and high-energy astrophysics. The hypothesis posits that these objects may constitute a substantial fraction of dark matter, simultaneously accounting for the observed dark matter abundance and the origin of the detected neutrino.

Unlike four-dimensional PBHs, their 5D counterparts exhibit altered characteristics. For a given mass, 5D PBHs are larger, cooler, and have longer lifespans, significantly influencing their decay mechanisms and observational signatures. These properties allow 5D PBHs to decay almost invisibly to observers confined to our three-dimensional ‘brane’ – the observable universe – primarily emitting through gravitational interactions rather than readily detectable particles.

The research team proposes that 5D PBHs undergo a final-stage emission flare of Standard Model particles, including neutrinos, during terminal evaporation. This flare, though brief, releases considerable energy, potentially accounting for the KM3-230213A event. By modelling the evaporation process and considering the unique properties of 5D PBHs, the researchers demonstrate that this scenario is consistent with existing observational constraints.

The study meticulously calculates the expected energy spectrum and event rate for neutrino emission from evaporating 5D PBHs, comparing the results with the observed characteristics of KM3-230213A. The calculations reveal a correlation between the predicted neutrino signal and the observed event, supporting the 5D PBH hypothesis.

The analysis demonstrates that the observed neutrino event falls within the predicted parameter space for 5D PBH evaporation, strengthening the case for this exotic dark matter candidate. This consistency with observational data, coupled with the theoretical advantages of 5D PBHs, makes this scenario a promising area for future research.

Researchers carefully considered the implications of this model for existing dark matter searches, demonstrating that the predicted signal is consistent with upper limits established by the IceCube Neutrino Observatory. This consistency highlights the viability of this exotic dark matter candidate.

The study also explores the implications for other areas of astrophysics, such as the origin of ultra-high-energy cosmic rays. Evaporating 5D PBHs could contribute to the observed flux of cosmic rays, offering a potential explanation for these energetic particles.

The research team emphasises that this is a testable hypothesis. They propose specific observational strategies for detecting additional neutrino events from evaporating 5D PBHs, outlining the characteristics of the expected signal and the optimal detection techniques.

Researchers acknowledge that further research is needed to fully understand the properties of 5D PBHs and their potential contribution to the dark matter abundance. They plan to conduct more detailed simulations of PBH formation and evolution, incorporating various cosmological parameters and astrophysical processes. These simulations will refine the model’s predictions and guide future observational searches.

The team believes that this study represents a step forward in our understanding of dark matter and high-energy astrophysics. By proposing a novel dark matter candidate and providing a compelling explanation for the KM3-230213A neutrino event, they have opened up new avenues for research.

The study concludes that five-dimensional primordial black holes offer a compelling and testable explanation for the observed high-energy neutrino signal, potentially resolving long-standing puzzles in dark matter research and astrophysics. By combining theoretical modelling with observational constraints, the researchers have demonstrated the viability of this exotic dark matter candidate and paved the way for future investigations.