三维螺旋臂cosmic-ray源分布模型中的传播和使用PICARD的二次粒子产生
Propagation in 3D spiral-arm cosmic-ray source distribution models and secondary particle production using PICARD
摘要：
我们研究了银河系宇宙射线源的可能的螺旋臂分布对整个银河系各种宇宙射线核通量的影响。我们调查模型宇宙射线光谱在标称位置的太阳和银河系内的不同位置。使用最近推出的数值宇宙射线传播代码\textsc{Picard}进行建模。假设非轴对称的宇宙射线源分布产生新的见解的行为，初级与次级核。我们发现，初级宇宙射线更强烈地局限于附近的源，而次级宇宙射线的分布是更均匀的相比，初级。与轴对称源分布模型相比，这导致次级与初级比率的空间变化更强。在不同的旋臂模型中可以很好地拟合地球上的宇宙射线数据，尽管这会导致宇宙射线通量的决定性不同的空间分布。这导致了非常不同的宇宙射线各向异性，甚至可以很好地拟合数据。因此，我们主张方向，以寻求最适合的传播参数，考虑到更高的复杂性所引入的螺旋臂结构的宇宙射线分布。我们专门研究地球上的通量是否代表了银河系的一大部分。可能的螺旋臂模型之间的差异，使我们能够量化的空间变化的宇宙射线流量在银河系内存在的非轴对称源分布。
英文摘要：
We study the impact of possible spiral-arm distributions of Galactic cosmic-ray sources on the flux of various cosmic-ray nuclei throughout our Galaxy. We investigate model cosmic-ray spectra at the nominal position of the sun and at different positions within the Galaxy. The modelling is performed using the recently introduced numerical cosmic ray propagation code \textsc{Picard}. Assuming non-axisymmetric cosmic ray source distributions yields new insights on the behaviour of primary versus secondary nuclei. We find that primary cosmic rays are more strongly confined to the vicinity of the sources, while the distribution of secondary cosmic rays is much more homogeneous compared to the primaries. This leads to stronger spatial variation in secondary to primary ratios when compared to axisymmetric source distribution models. A good fit to the cosmic-ray data at Earth can be accomplished in different spiral-arm models, although leading to decisively different spatial distributions of the cosmic-ray flux. This results in very different cosmic ray anisotropies, where even a good fit to the data becomes possible. Consequently, we advocate directions to seek best fit propagation parameters that take into account the higher complexity introduced by the spiral-arm structure on the cosmic-ray distribution. We specifically investigate whether the flux at Earth is representative for a large fraction of the Galaxy. The variance among possible spiral-arm models allows us to quantify the spatial variation of the cosmic-ray flux within the Galaxy in presence of non-axisymmetric source distributions.
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