A Turbulence-Driven Magnetic Reconnection Model for the High-Energy Neutrino Emission from NGC 1068

TL;DR

This paper proposes a turbulence-driven magnetic reconnection model in the nuclear region of NGC 1068 to explain its high-energy neutrino emission, matching observations and suggesting efficient proton acceleration.

Contribution

It introduces a novel model where turbulence-induced magnetic reconnection accelerates protons in the inner AGN region, explaining neutrino flux without detectable TeV gamma rays.

Findings

Model reproduces observed spectral energy distribution of NGC 1068.

Protons reach energies of ~10^{14} eV via first-order Fermi acceleration.

Neutrino production via pp interactions matches IceCube observations.

Abstract

We model the Seyfert II AGN NGC 1068 within a turbulence-induced magnetic reconnection framework to explain its high-energy emission. Observations reveal a neutrino flux excess higher than the observed GeV gamma-ray emission by orders of magnitude, with no detected TeV counterpart, suggesting efficient hadronic acceleration in the nuclear region with strong gamma-ray absorption. Assuming that proton acceleration occurs in a turbulent reconnection layer via a first-order Fermi process, we use a lepto-hadronic model based on a coronal-accretion disk configuration in which magnetic field lines anchored to the $2 \times 10^{7} M_{\odot}$ black hole horizon reconnect with field lines from the inner accretion disk corona. Our model matches the observed spectral energy distribution with a magnetic field $B_{c} \sim 10^{4}$ G and magnetic reconnection power $\dot{W_{B}} \sim 10^{43}$ erg s$^{-1}$, with $\sim 50\%$ efficiency in proton acceleration. Unlike previous studies, we find that both particle acceleration and emission take place in the inner region, where protons reach $\sim 10^{14}$ eV via first-order Fermi acceleration within the turbulent reconnection layer, rather than drift acceleration. These protons interact with disk photons, coronal X-rays, and coronal protons, producing neutrinos, predominantly via $pp$ interactions, at levels consistent with IceCube detections. The associated gamma-rays are attenuated by $\gamma\gamma$ annihilation, remaining below current upper limits. Turbulence-driven reconnection is thus a viable mechanism for neutrino production in the coronal region of NGC 1068 and similar sources.