论文标题
外层次宇宙射线从两个来源扩散
Extragalactic cosmic rays diffusing from two populations of sources
论文作者
论文摘要
我们考虑在湍流间层状磁场的情况下，用两个不同的外层次源来解释宇宙射线的观察到的频谱和宇宙射线的组成和能量以上的能量高于$ 10^{17} $ eV（包括褪色的银河系宇宙射线射线组件）。人群被认为是具有刚度依赖性光谱的不同核种的叠加。第一个外乳癌种群在能源范围内占主导地位$ 10^{17} $至$ 10^{18} $ eV，由具有相对较大密度的来源组成（$> 10^{ - 3} $ MPC $^{ - 3} $）和陡峭的频谱。第二个外层次群体主导着宇宙射线的通量，它的光谱斜率更难，并且在几个$ z $ eev（其中$ ez $是相关的宇宙射线电荷）中具有高能量的截止。该人群的来源密度较低（$ <10^{ - 4} $ MPC $^{ - 3} $），因此典型的媒介间隔大于几十MPC，受到了磁性地平线效应的显着影响，从而强烈抑制了其在$ sim s z $ eev下的能源的范围。我们讨论如何将这种情况与宇宙射线源光谱指数的值进行调和，这些镜头源光谱指数有望由扩散的冲击加速度机制造成。
We consider the possibility of explaining the observed spectrum and composition of the cosmic rays with energies above $10^{17}$ eV in terms of two different extragalactic populations of sources in the presence of a turbulent intergalactic magnetic field (including also a fading Galactic cosmic-ray component). The populations are considered to be the superposition of different nuclear species having rigidity dependent spectra. The first extragalactic population is dominant in the energy range $10^{17}$ to $10^{18}$ eV and consists of sources having a relatively large density ($> 10^{-3}$ Mpc$^{-3}$) and a steep spectrum. The second extragalactic population dominates the cosmic ray flux above few EeV, it has a harder spectral slope and has a high-energy cutoff at few $Z$ EeV (where $eZ$ is the associated cosmic ray charge). This population has a lower density of sources ($<10^{-4}$ Mpc$^{-3}$), so that the typical intersource separation is larger than few tens of Mpc, being significantly affected by a magnetic horizon effect that strongly suppresses its flux for energies below $\sim Z$ EeV. We discuss how this scenario could be reconciled with the values of the cosmic-ray source spectral indices that are expected to result from the diffusive shock acceleration mechanism.
