SIMBAD references

The origin of TeV-PeV neutrinos detected by IceCube remains largely unknown. The most significant individual neutrino source is the Seyfert galaxy NGC 1068 with a soft spectrum. Another notable candidate is the Seyfert galaxy NGC 7469, which has been recently proposed as a potential neutrino emitter. The likelihood fit of the IceCube data for this source returned a hard spectral index of ∼1.9, and the excess is dominated by two high-energy events. The energies of these two neutrinos are estimated to be 100-200 TeV, implying a maximum proton energy ${E}_{p,{\rm{\max }}}\gt 2\,{\rm{PeV}}$, significantly higher than that in NGC 1068. In this paper, we analyze the Fermi Large Area Telescope observations of NGC 7469, which yield nondetection. The size of the neutrino-emitting region can be constrained by the nondetection when the neutrino flux takes a high value in the allowed range. We suggest that cosmic-ray protons are accelerated to PeV energies via turbulence or magnetic reconnection in the corona and produce ∼100-200 TeV neutrinos via the pγ process. In the turbulence acceleration scenario, the required maximum proton energy can be achieved with a magnetization parameter of σ ∼ 1, while in the reconnection scenario, a magnetization parameter with σ ∼ 10 is needed. In both scenarios, a pair-dominated composition for the corona is preferred. The difference in the neutrino spectrum between NGC 7469 and NGC 1068 could be due to a different magnetization parameter despite the fact that they belong to the same type of active galactic nucleus.