Ultra-High-Energy Cosmic Rays from Neutrino-Emitting Tidal Disruption Events

TL;DR

This paper investigates the potential of tidal disruption events (TDEs) to produce ultra-high-energy cosmic rays and associated neutrinos, proposing a model linking TDE characteristics with observed cosmic ray and neutrino data.

Contribution

It introduces a source-propagation model connecting TDEs with UHECRs and neutrinos, and infers source composition, population parameters, and rates consistent with observations.

Findings

UHECR data suggest a mix of light to mid-heavy nuclei.

At least two TDE groups contribute to UHECRs, dominated by AT2019aalc-like events.

Predicted neutrino fluxes are detectable by future radio neutrino experiments.

Abstract

We revisit the Ultra-High-Energy Cosmic Ray (UHECRs) production in Tidal Disruption Events (TDEs) in the light of recent neutrino-TDE associations. We use an isotropically emitting source-propagation model, which has been developed to describe the neutrino production in AT2019dsg, AT2019fdr, and AT2019aalc. These TDEs have strong dust echoes in the infrared range, which are potentially linked with the neutrino production. A mechanism where neutrinos originate from cosmic ray scattering on infrared photons implies cosmic rays in the ultra-high energy range, thus suggesting a natural connection with the observed UHECR. We extrapolate the three TDE associations to a population of neutrino- and UHECR-emitting TDEs, and postulate that these TDEs power the UHECRs. We then infer the source composition, population parameters, and local rates that are needed to describe UHECR data. We find that UHECR data point towards a mix of light to mid-heavy injection isotopes, which could be found, e.g., in oxygen-neon-magnesium white dwarfs, and to a contribution of at least two groups of TDEs with different characteristics, dominated by AT2019aalc-type events. The required local TDE rates of ${\mathcal O}(10^2)~\mathrm{Gpc^{-3} \, yr^{-1}}$, however, are more indicative of the disruption of main sequence stars. We propose an enhanced efficiency in the acceleration of heavier nuclei that could address this discrepancy. The predicted diffuse neutrino fluxes suggest a population of astrophysical neutrino sources that can be observed by future radio neutrino detection experiments. The derived source parameters are consistent with those expected from the individual neutrino observations.