Title: Diffuse Neutrino Intensity from the Inner Jets of Active Galactic Nuclei: Impacts of External Photon Fields and the Blazar Sequence Show Chinese title

Title: 活动星系核内 jets 的弥散中微子强度：外部光子场和耀变体序列的影响

Abstract: We study high-energy neutrino production in inner jets of radio-loud active galactic nuclei (AGN), taking into account effects of external photon fields and the blazar sequence. We show that the resulting diffuse neutrino intensity is dominated by quasar-hosted blazars, in particular, flat spectrum radio quasars, and that PeV-EeV neutrino production due to photohadronic interactions with broadline and dust radiation is unavoidable if the AGN inner jets are ultrahigh-energy cosmic-ray (UHECR) sources. Their neutrino spectrum has a cutoff feature around PeV energies since target photons are due to Ly$\alpha$ emission. Because of infrared photons provided by the dust torus, neutrino spectra above PeV energies are too hard to be consistent with the IceCube data unless the proton spectral index is steeper than 2.5, or the maximum proton energy is $\lesssim100$ PeV. Thus, the simple model has difficulty in explaining the IceCube data. For the cumulative neutrino intensity from blazars to exceed $\sim{10}^{-8}~{\rm GeV}~{\rm cm}^{-2}~{\rm s}^{-1}~{\rm sr}^{-1}$, their local cosmic-ray energy generation rate would be $\sim10-100$ times larger than the local UHECR emissivity, but is comparable to the averaged gamma-ray blazar emissivity. Interestingly, future detectors such as the Askaryan Radio Array can detect $\sim0.1-1$ EeV neutrinos even in more conservative cases, allowing us to indirectly test the hypothesis that UHECRs are produced in the inner jets. We find that the diffuse neutrino intensity from radio-loud AGN is dominated by blazars with gamma-ray luminosity of $\gtrsim10^{48}~{\rm erg}~{\rm s}^{-1}$, and the arrival directions of their $\sim1-100$ PeV neutrinos correlate with the luminous blazars detected by Fermi. Show Chinese abstract

Abstract: 我们研究射电明亮活动星系核（AGN）内 jets 中高能中微子的产生，考虑到外部光子场和耀变体序列的影响。 我们表明，产生的弥散中微子强度主要由宿主类星体的耀变体主导，特别是平谱射电类星体，并且如果 AGN 内 jets 是超高能宇宙射线（UHECR）源，则由于与宽线和尘埃辐射的光核相互作用导致的 PeV-EeV 中微子产生是不可避免的。 由于目标光子来自 Ly$\alpha$发射，它们的中微子谱在 PeV 能量附近具有截止特征。 由于尘埃环提供的红外光子，除非质子谱指数比 2.5 更陡，或者最大质子能量为$\lesssim100$PeV，否则 PeV 以上的中微子谱太硬，无法与 IceCube 数据一致。 因此，简单的模型难以解释 IceCube 数据。 为了使耀变体的累积中微子强度超过$\sim{10}^{-8}~{\rm GeV}~{\rm cm}^{-2}~{\rm s}^{-1}~{\rm sr}^{-1}$，其局部宇宙射线能量生成率将比局部 UHECR 辐射度大$\sim10-100$倍，但与平均伽马射线耀变体辐射度相当。 有趣的是，未来的探测器如 Askaryan Radio Array 即使在更保守的情况下也能探测到$\sim0.1-1$EeV 中微子，使我们能够间接检验 UHECR 在内 jets 中产生的假设。 我们发现，射电明亮 AGN 的弥散中微子强度由伽马射线光度为$\gtrsim10^{48}~{\rm erg}~{\rm s}^{-1}$的耀变体主导，它们的$\sim1-100$PeV 中微子到达方向与 Fermi 探测到的明亮耀变体相关。