发表机构
State Key Laboratory of Dark Matter Physics, Tsung-Dao Lee Institute & School of Physics and Astronomy, Shanghai Jiao Tong University（暗物质物理国家重点实验室、李政道研究所及上海交通大学物理与天文学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
通过分析0.1至1000 PeV的质子与氦光谱，发现宇宙射线膝不支持单一截断，需有延伸至100 PeV以上的质子成分，可能源于谱断裂或连续延伸，揭示银河系输运与极端加速器的作用。
AI 中文摘要
宇宙射线（CR）在几拍电子伏特（PeV）处的“膝”通常与银河系质子的加速极限相关。最近从微类星体天鹅座X-3探测到的多PeV光子表明质子可被加速至数十PeV。然而，此类源对宇宙射线的贡献仍不清楚。在此，我们分析了覆盖0.1至1000 PeV的质子和氦光谱数据，发现膝部强烈不支持单一终端截断。包含低至数十吉电子伏特（GeV）测量的全谱分析要求质子贡献延伸至超过100 PeV。该贡献要么从GeV连续延伸至100 PeV能量，要么属于一个在膝部具有谱断裂的独立成分。在源族群解释中，其与较低能量银河宇宙射线的联系表明其具有银河系起源。从GeV能量起的成分通常与超新星遗迹相关，但将其延伸至超过100 PeV对加速理论和普通遗迹的γ射线观测构成挑战。相比之下，谱断裂可以自然地由依赖于刚度的输运产生。这种解释使膝成为探测银河系宇宙射线输运的探针，并将延伸的质子谱与极端银河系加速器（如超爱丁顿X射线双星）联系起来，这些加速器也能产生PeVγ射线和中微子。
英文摘要
The cosmic-ray (CR) \textit{knee} at a few petaelectronvolts (PeV) is commonly associated with the acceleration limit of Galactic protons. Recent detection of multi-PeV photons from the microquasar Cygnus X-3 suggests proton acceleration to tens of PeV. However, the contribution of such type of sources to CRs remains unclear. Here we analyse proton and helium spectral data spanning from 0.1 to 1000~PeV and find that the knee strongly disfavours a single terminal cutoff. Full-spectrum analyses incorporating measurements down to tens of gigaelectronvolts (GeV) require a proton contribution extending beyond $100\,\mathrm{PeV}$. This contribution either extends continuously from GeV to 100~PeV energies or belongs to a distinct component whose spectrum has a spectral break at the knee. Within source-population interpretations, its connection to lower-energy Galactic cosmic rays suggests a Galactic origin. The component from GeV energies is conventionally associated with supernova remnants, but extending it beyond $100\,\mathrm{PeV}$ challenges acceleration theory and $γ$-ray observations of ordinary remnants . A spectral break, by contrast, can arise naturally from rigidity-dependent transport. This interpretation makes the knee a probe of Galactic CR transport, and connects the extended proton spectrum to extreme Galactic accelerators, such as super-Eddington X-ray binaries, that can also produce PeV $γ$ rays and neutrinos.
Comments5 pages main text with 2 figures + 5 pages appendix with 1 figure, submitted on Sep 18
