Recent data from the Pierre Auger Observatory has revealed the presence of a large-scale dipole in the arrival direction distribution of ultrahigh-energy cosmic rays (UHECR). In this work, we build up an understanding of the diffusive origin of such a dipolar behavior as well as its dependency on energy and astrophysical source assumptions such as extra-Galactic magnetic field strength and cosmic ray composition. We present a novel analytical approach for calculating the angular distribution of CR coming from a single source and discuss the regimes in which the steady-state dipole result is expected. We also present a semianalytical method for calculating the evolution with energy of the resultant dipole for an ensemble of sources. We show that a local source allows for a strong growth of the dipole with energy over a large energy range. The possibility of a transition from a dipolar to nondipolar regime at the highest energies and its implications for the source density, magnetic field intensity, and cosmic ray composition are discussed.

中文翻译：

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超高能宇宙射线偶极及以上

皮埃尔·奥格天文台的最新数据显示，超高能宇宙射线（UHECR）的到达方向分布中存在一个大型偶极子。在这项工作中，我们建立了对这种偶极行为的扩散起源及其对能量和天体物理源假设（例如银河系外磁场强度和宇宙射线成分）的依赖性的理解。我们提出了一种新颖的分析方法，用于计算来自单一来源的CR的角分布，并讨论了预期稳态偶极子结果的机制。我们还提出了一种半解析方法，用于计算一组源的合成偶极子随能量的演化。我们表明，本地能量源可以在很大的能量范围内使偶极子的能量强劲增长。