Year: 2026
Type: article
Abstract: Context. Jetted active galactic nuclei aligned with our line of sight known as blazars are promising high-energy neutrino source candidates. However, leptohadronic models face challenges in describing neutrino emission within a viable energy budget and their predictive power are limited by the commonly used single-zone approximation and reliance on phenomenological parameters. Aims. We tested the scenario where energetic protons are continuously accelerated up to ultra-high energies in inner blazar jets, while accounting for the source energetics and jet dynamics. Methods. We present a new leptohadronic model, where a sub-Eddington jet evolves from being magnetically to kinetically dominated. A constant fraction of 10−6–10−8 of the electrons and protons picked up by the jet are continuously accelerated to a power-law spectrum. We can estimate their normalization and maximum energies based on the local magnetic field strength, turbulence, and medium density, for which we assumed power-law profiles. The model parameters are thus directly tied to the jet physics and are comparable in number to a single-zone model. We then calculate the emission along the jet, including neutrinos and electromagnetic cascades. Results. Applying the model to IceCube candidate TXS 0506+056, we find that protons accelerated in the inner jet produce a neutrino flux up to ∼100 PeV that is consistent with the public IceCube ten-year point-source data. Proton emission at 0.1 pc describes the X-ray and γ-ray data, while electron emission at the parsec scale describes the optical data. Protons carry a power of about 1% of the Eddington luminosity. The particle spectra follow E−1.8, with diffusion scaling as E0.3, ruling out Bohm-like diffusion. Additional particle injection near the broad line region can reproduce the 2017 flare associated to a high-energy neutrino. We also applied the model to the blazar PKS 0605-085, which could be associated with a recent neutrino detected by KM3NeT above 100 PeV. Conclusions. Magnetic acceleration in blazar jets can describe multimessenger observations with viable energetics. Our model constrains jet properties such as the energy-dependent particle diffusion and predicts the spatial distribution of the multiwavelength and neutrino emission along the jet. The results suggest that blazars are efficient neutrino emitters at ultra-high energies, making them prime candidates for future experiments targeting this challenging energy range.
Authors: X. Rodrigues, F. Rieger, A. Bohdan, P. Padovani
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G1610782679, G2004548919, G2610760373, G2897595177, Idex Paris-Saclay, G3408140573, G4066435496, EXC 2094: ORIGINS: Vom Ursprung des Universums bis zu den ersten Bausteinen des Lebens, G463759079, G4810098524, G4866930200, G5263632016, G7240651115, G7376787254, Physics of the 2 infinities and the origins
OpenAlex ID: W7122440858
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