Ultrarelativistic particles called cosmic rays permeate the Milky Way, propagating through the turbulent Galactic magnetic fields. The mechanisms under which these particles increase their energy can be reasonably described by current theories of acceleration and propagation of cosmic rays. There are, however, still many open questions as to how to reach petaelectronvolt (PeV) energies, the maximum energy believed to be attained in our Galaxy, and in which astrophysical sources (dubbed PeVatrons) this ultrahigh-energy acceleration happens. In this Review, we describe the theoretical conditions for plasma acceleration to these energies and the Galactic sources in which these conditions are possible. These theoretical predictions are then compared to the latest experimental results, summarizing the state of the art of our current knowledge of PeVatrons. We finally describe the prospects to keep advancing the understanding of these elusive objects, still unidentified more than 100 years after the discovery of cosmic rays.

被称为宇宙射线的超相对论粒子遍布银河系，并通过湍流的银河磁场传播。这些粒子增加能量的机制可以通过当前的宇宙射线加速和传播理论合理地描述。然而，关于如何达到千万电子伏特（PeV）能量（据信在我们的银河系中可以达到的最大能量）以及在哪些天体物理源（称为 PeVatrons）中发生这种超高能量加速，仍然存在许多悬而未决的问题。在这篇评论中，我们描述了等离子体加速这些能量的理论条件以及这些条件可能存在的银河源。然后将这些理论预测与最新的实验结果进行比较，总结我们目前对 PeVatrons 的了解的最新水平。我们最后描述了继续推进对这些难以捉摸的物体的理解的前景，这些物体在宇宙射线发现 100 多年后仍然未被识别。