AGN电场中超高能宇宙线成分依赖的加速效应
Composition-dependent acceleration of UHE Cosmic Rays in AGN electric fields
- National and Kapodistrian University of Athens（雅典国立卡波季斯特里安大学）
- Academy of Athens（雅典科学院）
- NASA Goddard Space Flight Center（美国宇航局戈达德太空飞行中心）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究通过建立电压降加速与簇射观测量联系，发现质子贫乏注入在10和30 Mpc处拟合Auger数据最佳，表明簇射宽度可约束AGN电场加速的随机结构。
AI中文摘要：
超高能宇宙线（UHECRs）的起源仍难以捉摸，因为所提出的加速机制很少与对成分敏感的气簇射观测量直接相关。我们为超大质量黑洞周围磁 arrested 盘近地平线电流片中的电压降加速建立了这种联系。碎裂通过有效电势采样因子 $\eta$ 的对数正态分布来表示，其中 $\mu_\eta=\langle\ln\eta\rangle$，$\sigma_\eta=[\mathrm{Var}(\ln\eta)]^{1/2}$，中位数 $\widetilde{\eta}=e^{\mu_\eta}$，而能量增益与核电荷 $Z$ 和最大电势 $\mathcal{V}_{\max}$ 成比例。我们通过 Bethe-Heitler 过程和绝热损失、质子光介子衰减以及质量演化的光致蜕变级联来传播加速粒子，并预测 $\langle X_{\max}\rangle$ 和 $\sigma(X_{\max})$。我们对 Pierre Auger 天文台 2025 年 DNN 测量数据进行贝叶斯拟合，采用两种固定注入模板以及 10、30 和 100 Mpc 的传播距离。一种受 Auger 启发的、质子贫乏的注入在 10 和 30 Mpc 处重现了两个簇射矩，$\chi^2/\nu=0.33$ 和 $0.47$。在 30 Mpc 处，$\sigma_\eta=0.59^{+0.13}_{-0.10}$，对应约 1.8 的乘性离散。中位数采样因子和最大电势保持强简并，而 $\widetilde{\eta}\mathcal{V}_{\max}$ 受到更直接的约束。一种富含金属的注入（含约 $53\\%$ 氢）在 10 和 30 Mpc 处的 $\chi^2$ 分别大 17.9 和 25.9。两种模板在 10 和 30 Mpc 处均可行，但在 100 Mpc 处拟合较差。在所测试的情景中，结果倾向于相对质子贫乏的加速粒子群，并表明簇射宽度演化可以约束附近 AGN 中电场加速的随机结构。
英文摘要：
The origin of ultra-high-energy cosmic rays (UHECRs) remains elusive, as proposed acceleration mechanisms are rarely connected directly to composition-sensitive air-shower observables. We establish such a connection for voltage-drop acceleration in near-horizon current sheets of magnetically arrested disks around supermassive black holes. Fragmentation is represented by a log-normal distribution of effective potential-sampling factors $η$, with $μ_η=\langle\lnη\rangle$, $σ_η=[\mathrm{Var}(\lnη)]^{1/2}$, and median $\widetildeη=e^{μ_η}$, while the energy gain scales with nuclear charge $Z$ and maximum potential $\mathcal{V}_{\max}$. We propagate the accelerated particles through Bethe--Heitler and adiabatic losses, proton photopion attenuation, and a mass-evolving photodisintegration cascade, and predict $\langle X_{\max}\rangle$ and $σ(X_{\max})$. We perform Bayesian fits to the Pierre Auger Observatory 2025 DNN measurements for two fixed injection templates and propagation distances of 10, 30, and 100 Mpc. An Auger-inspired, proton-poor injection reproduces both shower moments at 10 and 30 Mpc, with $χ^2/ν=0.33$ and $0.47$. At 30 Mpc, $σ_η=0.59^{+0.13}_{-0.10}$, corresponding to a multiplicative dispersion of approximately 1.8. The median sampling factor and maximum potential remain strongly degenerate, with $\widetildeη\mathcal{V}_{\max}$ more directly constrained. A metal-enriched injection containing $\sim53\%$ hydrogen gives $χ^2$ larger by 17.9 and 25.9 at 10 and 30 Mpc. Both templates remain viable at 10 and 30 Mpc but fit poorly at 100 Mpc. Within the scenarios tested, the results favour a relatively proton-poor accelerated population and show that the shower-width evolution can constrain the stochastic structure of electric-field acceleration in nearby AGN.
