Explaining the PeV Neutrino Fluxes at KM3NeT and IceCube with Quasi-Extremal Primordial Black Holes

Abstract

The KM3NeT experiment has recently observed a neutrino with an energy around 100PeV, and IceCube has detected five neutrinos with energies above 1PeV. While there are no known astrophysical sources, exploding primordial black holes could have produced these high-energy neutrinos. For Schwarzschild black holes this interpretation results in tensions between the burst rates inferred from the KM3NeT and IceCube observations, with indirect constraints from the extragalactic gamma ray background and with the non-observation of an associated gamma ray signal at LHAASO. In this letter we show that if there is a population of primordial black holes charged under a new dark $u(1)$ symmetry which spend most of their time in a quasi-extremal state, the neutrino emission at 1PeV may be more suppressed than at 100PeV. The burst rates implied by the KM3NeT and IceCube observations and the indirect constraints can then all be consistent at $1σ$, and no associated gamma-ray signal was expected at LHAASO. Furthermore, these black holes could constitute all of the observed dark matter in the universe.

Figures (3)

• Figure 1: Time integrated neutrino spectra during the explosion of Schwarzschild (black) and Reissner–Nordström (colour) black holes for different dark electron masses and couplings. We take $Q_D^{*i} = 0.01$ and $M_\text{PBH}^i= 5.6\times 10^{14}$ g, $3.5\times 10^{7}$ g, $3.7\times 10^{6}$ g, $3.9\times 10^{5}$ g and $7.2\times 10^{4}$ g for the black, blue, green, red and orange curves, respectively. We integrate over the last 0.09s, 0.62s, 0.48s, 0.23s and 0.15s, respectively, according to the prescription described in the text. The blue bands indicate the IceCube and KM3NeT neutrino energy ranges.
• Figure 2: Ratio of the burst rate inferred by the KM3NeT flux over that inferred by the IceCube flux for several dark electron masses, as a function of the dark coupling. The coloured bands correspond to the $1\sigma$ error. The coloured dot indicates the point beyond which our evolution equations are not applicable, while perturbativity requires $e_D<\sqrt{4\pi}$.
• Figure 3: Burst rates inferred by KM3NeT (purple) and IceCube (brown) with their $1\sigma$ error bands for $m_D=10^{15}$GeV. The black lines indicate the maximum allowed burst rate by indirect constraints assuming a log-normal (LN) mass distribution with $\sigma=0.3$ and a generalized critical collapse (CC) distribution with $\alpha=5.76$ and $\beta=0.51$Gow:2020cou. The $\times$ and $+$ indicate the same parameter points as in \ref{['fig:BurstRatio']}.