Cosmic rays (protons and other atomic nuclei) are believed to gain energies of petaelectronvolts (PeV) and beyond at astrophysical particle accelerators called ‘PeVatrons’ inside our Galaxy. Although a characteristic feature of a PeVatron is expected to be a hard gamma-ray energy spectrum that extends beyond 100 teraelectronvolts (TeV) without a cut-off, none of the currently known sources exhibit such a spectrum owing to the low maximum energy of accelerated cosmic rays or owing to insufficient detector sensitivity around 100 TeV. Here, we report the observation of gamma-ray emission from the supernova remnant G106.3+2.7 (refs. ^1,2) above 10 TeV. This work provides flux data points up to and above 100 TeV and indicates that the very-high-energy gamma-ray emission above 10 TeV is well correlated with a molecular cloud³ rather than with the pulsar PSR J2229+6114 (refs. ^4,5,6,7,8). Regarding the gamma-ray emission mechanism of G106.3+2.7, this morphological feature appears to favour a hadronic origin via the π⁰ decay caused by accelerated relativistic protons⁹ over a leptonic origin via the inverse Compton scattering by relativistic electrons^10,11. Furthermore, we point out that an X-ray flux upper limit on the synchrotron spectrum would provide important information to firmly establish the hadronic scenario as the mechanism of particle acceleration at the source.

宇宙射线（质子和其他原子核）被认为在我们银河系内部称为“PeVatrons”的天体物理粒子加速器中获得拍电子伏特 (PeV) 及更高的能量。尽管预计 PeVatron 的一个特征是一个硬伽马射线能谱，其延伸超过 100 兆电子伏特 (TeV) 而没有截止，但由于加速的最大能量低，目前已知的源都没有表现出这样的光谱。宇宙射线或由于 100 TeV 左右的探测器灵敏度不足。在这里，我们报告了对超新星遗迹 G106.3+2.7 的伽马射线发射的观察（参考文献^1,2) 高于 10 TeV。这项工作提供了高达 100 TeV 及以上的通量数据点，并表明高于 10 TeV 的超高能伽马射线发射与分子云³而非脉冲星 PSR J2229+6114 密切相关（参考文献^{4， 5,6,7,8} )。关于 G106.3+2.7 的伽马射线发射机制，这种形态特征似乎有利于通过相对论电子^10,11的逆康普顿散射加速的相对论质子⁹引起的π ^{0衰变而不是轻子起源的强子起源}. 此外，我们指出同步加速器光谱上的 X 射线通量上限将为牢固确立强子情景作为源处粒子加速机制提供重要信息。