标题： 蟹状星云的PeV发射：脉冲星风中质子含量的限制及其启示 显示英文标题

标题： PeV emission of the Crab Nebula: constraints on the proton content in pulsar wind and implications

摘要： 近日，LHAASO从蟹状星云探测到两个能量约为1 PeV的光子，打开了研究脉冲星风星云（PWNe）的超高能窗口。 值得注意的是，LHAASO在最高能端的谱显示出一种可能的硬化现象，这可能表明存在新的成分。 为了解释整个蟹状星云的能谱，提出了一种双组分情景，即主要电子组分和次级质子组分，要求当前蟹状星云中剩余的质子能量为 $10^{46}-10^{47}{\rm ergs}$。 本文利用LHAASO的蟹状星云数据研究了脉冲星风中相对论质子的能量含量，并考虑了相对论质子扩散逃逸的影响。 根据相对论质子逃逸程度的不同，脉冲星风中损失的质子总能量可能是目前星云中剩余能量的10到100倍。 我们发现，当前的LHAASO数据允许脉冲星高达 $(10-50)\%$的减速能转化为相对论质子。 PWNe逃逸的质子可能会对10到100 PeV的宇宙射线流量做出相当大的贡献。 我们还讨论了PeV能量处可能的谱硬化现象的轻子情景。 显示英文摘要

摘要： Recently, two photons with energy of about 1 PeV have been detected by LHAASO from the Crab nebula, opening an ultra-high energy window for studying the pulsar wind nebulae (PWNe). Remarkably, the LHAASO spectrum at the highest-energy end shows a possible hardening, which could indicate the presence of a new component. A two-component scenario with a main electron component and a secondary proton component has been proposed to explain the whole spectrum of the Crab Nebula, requiring a proton energy of $10^{46}-10^{47}{\rm ergs}$ remaining in the present Crab Nebula. In this paper, we study the energy content of relativistic protons in pulsar winds with the LHAASO data of the Crab Nebula, considering the effect of diffusive escape of relativistic protons. Depending on the extent of the escape of relativistic protons, the total energy of protons lost in the pulsar wind could be 10-100 times larger than that remaining in the nebula presently. We find that the current LHAASO data allows up to $(10-50)\%$ of the spindown energy of pulsars being converted into relativistic protons. The escaping protons from PWNe could make a considerable contribution to the cosmic-ray flux of 10-100 PeV. We also discuss the leptonic scenario for the possible spectral hardening at PeV energies.