We demonstrate that a population of active galactic nuclei (AGN) can describe the observed spectrum of ultra-high-energy cosmic rays (UHECRs) at and above the ankle, and that the dominant contribution comes from low-luminosity BL Lacertae objects. An additional, subdominant contribution from high-luminosity AGN is needed to improve the description of the composition observables, leading to a substantial neutrino flux that peaks at exaelectronvolt (EeV) energies. We also find that different properties for the low- and high-luminosity AGN populations are required; a possibly similar baryonic loading can already be excluded from current IceCube Neutrino Observatory observations. We also show that the flux of neutrinos emitted from within the sources should outshine the cosmogenic neutrinos produced during the propagation of UHECRs. This result has profound implications for the ultra-high-energy ($\sim \mathrm{EeV}$) neutrino experiments, since additional search strategies can be used for source neutrinos compared to cosmogenic neutrinos, such as stacking searches, flare analyses, and multimessenger follow-ups.

中文翻译：

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主动银河核喷射器作为超高能宇宙射线的起源，并为EeV能量探测天体源中微子提供了前景。

我们证明了一个活跃的银河原子核（AGN）人口可以描述在脚踝处和脚踝以上的超高能宇宙射线（UHECRs）的光谱，并且主要的贡献来自低发光度BL Lacertae对象。需要来自高发光度AGN的额外的，主要的贡献来改善对可观察到的成分的描述，从而导致大量的中微子通量达到电纳伏（EeV）能量的峰值。我们还发现，低和高亮度AGN群体需要不同的属性。当前IceCube Neutrino天文台的观测值可能已经排除了可能类似的重子载荷。我们还表明，从源头内部发出的中微子通量应超过在UHECRs传播过程中产生的宇宙中微子。$〜\mathrm{病毒}$）中微子实验，因为与宇宙型中微子相比，其他搜索策略可用于源中微子，例如堆放搜索，火炬分析和多信使跟踪。