On the radial distribution of Galactic cosmic rays
On the radial distribution of Galactic cosmic rays
复制标题
银河系宇宙线的径向分布
DOI：
10.1093/mnrasl/slw136
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发表时间：
2016
影响因子：
4.8
通讯作者：
G. Morlino
中科院分区：
文献类型：
--
作者：
S. Recchia;P. Blasi;G. Morlino
银河系弥散伽马射线辐射的光谱和形态携带着宇宙射线（CR）传播的宝贵信息。最近的结果通过分析费米-LAT数据积累了七年的观测显示了CR光谱的函数从银河系中心的距离的实质性变化。在银河系的外部CR密度的空间分布似乎是弱依赖于银河系的距离，在以前的研究中发现，以及，而在银河系的中心区域的密度被发现超过在银河系的外部测量值。与此同时，费米-LAT数据表明，当从银河系中心向外移动到外围时，光谱逐渐软化。这些发现代表了一个挑战，CR传播的标准计算的基础上假设一个统一的扩散系数内的银河体积。在这里，我们提出了一个模型的非线性CR传播中，运输是由于粒子散射和平流关闭自生湍流。我们发现，对于一个现实的CR源的超新星遗迹的空间分布和磁场的空间依赖性的银河距离的空间分布，CR密度的空间分布和光谱软化可以很容易地占。
The spectrum and morphology of the diffuse Galactic gamma-ray emission carries valuable information on cosmic ray (CR) propagation. Recent results obtained by analyzing Fermi-LAT data accumulated over seven years of observation show a substantial variation of the CR spectrum as a function of the distance from the Galactic Center. The spatial distribution of the CR density in the outer Galaxy appears to be weakly dependent upon the galactocentric distance, as found in previous studies as well, while the density in the central region of the Galaxy was found to exceed the value measured in the outer Galaxy. At the same time, Fermi-LAT data suggest a gradual spectral softening while moving outward from the center of the Galaxy to its outskirts. These findings represent a challenge for standard calculations of CR propagation based on assuming a uniform diffusion coefficient within the Galactic volume. Here we present a model of non-linear CR propagation in which transport is due to particle scattering and advection off self-generated turbulence. We find that for a realistic distribution of CR sources following the spatial distribution of supernova remnants and the space dependence of the magnetic field on galactocentric distance, both the spatial profile of CR density and the spectral softening can easily be accounted for.