Mysteries about the origin of high-energy cosmic neutrinos have deepened by the recent IceCube measurement of a large diffuse flux in the 10–100 TeV range. Based on the standard disk-corona picture of active galactic nuclei (AGN), we present a phenomenological model enabling us to systematically calculate the spectral sequence of multimessenger emission from the AGN coronae. We show that protons in the coronal plasma can be stochastically accelerated up to PeV energies by plasma turbulence, and find that the model explains the large diffuse flux of medium-energy neutrinos if the cosmic rays carry only a few percent of the thermal energy. We find that the Bethe-Heitler process plays a crucial role in connecting these neutrinos and cascaded MeV gamma rays, and point out that the gamma-ray flux can even be enhanced by the reacceleration of secondary pairs. Critical tests of the model are given by its prediction that a significant fraction of the MeV gamma-ray background correlates with $\sim 10\mathrm{TeV}$ neutrinos, and nearby Seyfert galaxies including NGC 1068 are promising targets for IceCube, KM3Net, IceCube-Gen2, and future MeV gamma-ray telescopes.

中文翻译：

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作为中能量中微子起源的活跃银河核的隐藏核：MeV伽马射线连接的关键测试。

IceCube最近对10-100 TeV范围内的大扩散通量进行的测量表明，关于高能宇宙中微子起源的谜团已加深。基于活动银河原子核（AGN）的标准盘状日冕图片，我们提出了一种现象学模型，使我们能够系统地计算AGN日冕的多信使发射光谱序列。我们表明，通过等离子体湍流可以将冠状等离子体中的质子随机加速至PeV能量，并且发现该模型解释了如果宇宙射线仅携带百分之几的热能，则中能中微子的大扩散通量。我们发现Bethe-Heitler过程在连接这些中微子和级联的MeV伽玛射线中起着至关重要的作用，并指出，甚至可以通过次级对的重新加速来增强伽马射线通量。该模型的关键测试是通过预测得出的，其中很大一部分MeV伽玛射线背景与$〜10\mathrm{电视}$ 中微子和包括NGC 1068在内的赛弗特星系是IceCube，KM3Net，IceCube-Gen2和未来的MeV伽马射线望远镜的有希望的目标。