标题： 利用宇宙射线电子和正电子谱约束Gemina与地球之间的各向异性扩散 显示英文标题

标题： Constraining anisotropic diffusion between Geminga and Earth with the cosmic-ray electron and positron spectrum

摘要： 伽马射线晕围绕Geminga表明宇宙射线扩散有显著减少。 这一现象的一种可能解释是在各向异性扩散框架内，垂直于平均磁场的慢扩散投影效应（由扩散系数$D_\perp$表示）。 在这种情况下，平行于平均场的扩散系数（$D_\parallel$）可能仍然很大，使Geminga产生的电子和正电子（$e^\pm$）能够沿磁场线有效传播到地球，可能导致可观测的$e^\pm$流量。 本研究首先根据Geminga晕的形态和光谱观测确定各向异性模型的基本参数，然后预测Geminga在地球位置产生的$e^\pm$流量。 我们的研究结果表明，通过DAMPE获得的$e^-+e^+$谱可以为各向异性扩散模型提供关键约束：为了确保投影谱不超过观测数据，湍流磁场的阿尔芬马赫数($M_A$)不应低于0.75，对应于$D_\parallel/D_\perp\lesssim3$给出的$D_\perp=D_\parallel M_A^4$。这表明相对于银河系平均值，$D_\parallel$的显著减少可能仍然是必要的。此外，我们的分析显示，在各向异性扩散框架下，Geminga可能在$e^-+e^+$谱中产生一个约1 TeV的明显峰，可能解释了DAMPE初步检测到的异常1.4 TeV过量。 显示英文摘要

摘要： The gamma-ray halo surrounding Geminga suggests a notable reduction in cosmic-ray diffusion. One potential explanation for this phenomenon is the projection effect of slow diffusion perpendicular to the average magnetic field (represented by the diffusion coefficient $D_\perp$) within an anisotropic diffusion framework. In this context, the diffusion coefficient parallel to the mean field ($D_\parallel$) may remain substantial, allowing electrons and positrons ($e^\pm$) generated by Geminga to effectively propagate towards Earth along magnetic field lines, potentially leading to an observable $e^\pm$ flux. This study initially establishes the fundamental parameters of the anisotropic model based on the morphology and spectral observations of the Geminga halo, and subsequently forecasts the $e^\pm$ flux generated by Geminga at Earth's location. Our findings indicate that the $e^-+e^+$ spectrum obtained by DAMPE can provide critical constraints on the anisotropic diffusion model: to ensure that the projected spectrum does not surpass the observational data, the Alfv\'en Mach number of the turbulent magnetic field ($M_A$) should not fall below 0.75, corresponding to $D_\parallel/D_\perp\lesssim3$ given $D_\perp=D_\parallel M_A^4$. This suggests that a substantial reduction in $D_\parallel$ relative to the Galactic average may still be necessary. Additionally, our analysis reveals that within the anisotropic diffusion framework, Geminga could generate a distinct peak around 1 TeV in the $e^-+e^+$ spectrum, potentially accounting for the anomalous 1.4 TeV excess tentatively detected by DAMPE.