用IACT观测月球对宇宙电子和正电子的遮蔽
Observation of shadowing of the cosmic electrons and positrons by the Moon with IACT
摘要：
最近对宇宙射线电子（e-）和正电子（e+）通量的测量显示，与我们银河系中标准宇宙射线（CR）传播模型所预期的光谱相比，明显过量。这些过度可能与局部天体物理对象中的粒子加速有关，或者与暗物质湮灭/衰变有关。e+/e-比（测量到~100 GeV）意外地增加到10 GeV以上，这可能与在300-800 GeV的全电子通量中测量到的过量有关。在更高能量下测量这个比率是理解这些光谱异常起源的关键参数。成像大气切伦科夫望远镜（IACT）探测到100 GeV以上的电磁空气簇射，但是，使用这种技术，区分原始e-，e+和漫射伽马射线几乎是不可能的。然而，月球和地磁场提供了一个令人难以置信的机会来分离这三个组成部分。事实上，月球在各向同性的CR通量中产生了一个直径为0.5度的洞，地球磁层根据粒子的动量和电荷来移动CR通量。在几TeV以下，e+和e-的阴影在月球两侧移动> 0.5度，e+、e-和伽马射线的阴影在空间上是分离的。IACT可以观察到e+和e-阴影，但在视场中没有直射月光，但散射月光诱导了非常高的背景水平。MAGIC在最高海拔（2200米）运行，拥有目前IACT最大的望远镜（17米），是在这些特殊条件下达到低能量阈值的最佳候选者。在这里，我们讨论这种观察的可行性。
英文摘要：
Recent measurements of the cosmic-ray electron (e-) and positron (e+) fluxes show apparent excesses compared to the spectra expected by standard cosmic-ray (CR) propagation models in our galaxy. These excesses may be related to particle acceleration in local astrophysical objects, or to dark matter annihilation/decay. The e+/e- ratio (measured up to ~100 GeV) increases unexpectedly above 10 GeV and this may be connected to the excess measured in all-electron flux at 300-800 GeV. Measurement of this ratio at higher energies is a key parameter to understand the origin of these spectral anomalies. Imaging Atmospheric Cherenkov Telescopes (IACT) detect electromagnetic air showers above 100 GeV, but, with this technique, the discrimination between primary e-, e+ and diffuse gamma-rays is almost impossible. However, the Moon and the geomagnetic field provide an incredible opportunity to separate these 3 components. Indeed, the Moon produces a 0.5deg-diameter hole in the isotropic CR flux, which is shifted by the Earth magnetosphere depending on the momentum and charge of the particles. Below few TeV, the e+ and e- shadows are shifted at >0.5deg each side of the Moon and the e+, e- and gamma-ray shadows are spatially separated. IACT can observe the e+ and e- shadows without direct moonlight in the field of view, but the scattered moonlight induces a very high background level. Operating at the highest altitude (2200m), with the largest telescopes (17m) of the current IACT, MAGIC is the best candidate to reach a low energy threshold in these peculiar conditions. Here we discuss the feasibility of such observations.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
