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arXiv 1701.07136astro-ph.HEhep-ph
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从sub-TeV谱硬化看银河宇宙射线的膝关节

On the knee of Galactic cosmic rays in light of sub-TeV spectral hardenings

Yi-Qing Guo, Qiang Yuan

摘要:

在宇宙射线谱中发现膝关节50多年后,它的物理起源仍然是一个谜。这部分是由于单个成分的能谱的模糊性。最近,直接测量从几个气球/卫星携带的探测器发现显着的光谱硬化的宇宙射线核在几百个GV的刚度。对宇宙射线光谱的直接和间接测量进行联合建模可能有助于理解实验系统学,可能还有助于理解膝盖的物理学。在这项工作中,我们更新的现象学“多性腺”模型的膝盖,包括光谱硬化,与变化的光谱指数$γ+ β\cdot \log E$相对于能量。我们发现,有一些直接和间接测量之间的张力。具体来说,硬光谱的CREAM建议一个相对较低的能量截止的膝盖周围的个人宇宙射线光谱,这是不一致的轻组分光谱的空气淋浴测量。此外,AS $γ$ /ARGO-YBJ/WFCTA/KASCADE的轻组分数据与全粒子谱一致。我们期望通过运行空间探测器(如CALET和DAMPE)和地面实验(如LHAASO)对TeV能量及更高能量的单个成分的宇宙射线谱进行更精确的测量,最终将解决这些差异。最后,作为一个例子,我们证明了在双晕模型下的空间相关扩散能够重现这种“修改的多性腺”模型的结果。

英文摘要:

More than fifty years after the discovery of the knee in the cosmic ray spectra, its physical origin remains a mystery. This is partly due to the ambiguity of the energy spectrum of individual composition. Recently, direct measurements from several balloon/satellite-borne detectors found significant spectral hardenings of cosmic ray nuclei at a few hundred GV rigidities. A joint modeling of the direct and indirect measurements of the cosmic ray spectra may help to understand the experimental systematics and probably the physics of the knee. In this work, we update the phenomenological "poly-gonato" model of the knee to include the spectral hardenings, with a changing spectral index of $γ+ β\cdot \log E$ with respect to energy. We find that there is some tension between the direct and indirect measurements. Specifically, the hard spectra of CREAM suggest a relatively low energy cutoff of the individual cosmic ray spectrum around the knee, which is inconsistent with the light component spectra of the air shower measurements. Furthermore, the light component data from AS$γ$/ARGO-YBJ/WFCTA/KASCADE are consistent with the all-particle spectra. We expect that more precise measurements of the cosmic ray spectrum of individual composition at TeV energies and beyond by the operating space detectors such as CALET and DAMPE, and the ground based experiments such as LHAASO, will eventually solve these discrepancies. Finally, as an illustration, we show that a spatial-dependent diffusion under two-halo model is able to reproduce the results of this "modified poly-gonato" model.

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