Interplay between Accelerated Protons, Xrays and Neutrinos in the Corona of NGC 1068: Constraints from Kinetic Plasma Simulations

We examine properties of accelerated protons potentially responsible for the neutrino excess observed in the direction of NGC 1068, using constraints from kinetic particle-in-cell (PIC) simulations.  We find that: (i) coronal x-rays and optical/ultra-violet light in the inner disk lead to efficient absorption of hadronic γ-rays within 100 Schwarzschild radii from the black hole; (ii) protons accelerated from the coronal thermal pool cannot account for the observed neutrinos; and (iii) explaining the observed signal requires an injection of protons with a hard spectrum, peaking at γ_p∼10³−10⁴, into the turbulent magnetically-dominated corona, where they are confined and re-accelerate d. The resulting neutrino signal can be consistent with IceCube observations. In our most favorable scenario, the injected protons are pre-accelerated in intermittent current sheets in the vicinity of the black hole, occurring either at the boundary between the disk and the outflow or during magnetic flux eruption events.