超高能宇宙射线的起源：亚光速和超光速相对论激波
On the origin of ultra high energy cosmic rays: Subluminal and superluminal relativistic shocks
摘要：
超高能宇宙射线（UHECR）的流量在$E>10^{18.5}$ eV被认为是产生于等离子体冲击环境中的河外源。在本文中，我们提出了一个系统的研究粒子加速的相对论冲击，特别是关于体洛伦兹因子和磁场和冲击流之间的角度的依赖关系。首次系统地研究和比较了助推因子高达$Γ=1000$的超光速和亚光速激波的模拟结果。虽然超光速激波在最高能量（$E>10^{18.5}$ eV）下是无效的，但亚光速激波可以提供高达$10^{21}$ eV的粒子，仅受Hillas标准的限制。对于亚光速的情况下，我们发现，温和的相对论冲击，认为发生在喷流的活动星系核（AGN，$Γ\sim 10-30$）产生的能谱$dN/dE\sim E^{-2}$。另一方面，伽马射线暴（GRB，$100<Γ<1000$）中预期的高度相对论性冲击，其光谱与$E^{-1.5}$一样平坦。模型的结果进行了比较，在最高能量的宇宙射线的测量通量，它示出，而活动星系核光谱是非常合适的，伽玛射线暴光谱太平坦，无法解释所观察到的通量。该模型解释了$5.7\cdot 10^{10}$ GeV以上的宇宙线通量与活动星系核俄歇分布之间的相关性。中微子的产生预计在伽玛暴中，无论是在轻度或高度相对论性的冲击，虽然这些来源被排除作为UHECR的主要来源，超光速冲击，特别是可以通过中微子和光子通量，而不是质子观察。
英文摘要：
The flux of Ultra High Energy Cosmic Rays (UHECRs) at $E>10^{18.5}$ eV is believed to arise in plasma shock environments in extragalactic sources. In this paper, we present a systematic study of particle acceleration by relativistic shocks, in particular concerning the dependence on bulk Lorentz factor and the angle between the magnetic field and the shockflow. For the first time, simulation results of super- and subluminal shocks with boost factors up to $Γ=1000$ are investigated and compared systematically. While superluminal shocks are shown to be inefficient at the highest energies ($E>10^{18.5}$ eV), subluminal shocks may provide particles up to $10^{21}$ eV, limited only by the Hillas-criterion. For the subluminal case, we find that mildly relativistic shocks, thought to occur in jets of Active Galactic Nuclei (AGN, $Γ\sim 10-30$) yield energy spectra of $dN/dE\sim E^{-2}$. Highly relativistic shocks expected in Gamma Ray Bursts (GRBs, $100<Γ<1000$), on the other hand, have spectra as flat as $E^{-1.5}$. The model results are compared to the measured flux of Cosmic Rays at the highest energies and it is shown that, while AGN spectra are well-suited, GRB spectra are too flat to explain the observed flux. The first evidence of a correlation between the Cosmic Ray flux above $5.7\cdot 10^{10}$ GeV and the distribution of AGN by Auger are explained by the model. Neutrino production is expected in GRBs, either in mildly or highly relativistic shocks and although these sources are excluded as the principle origin of UHECRs, superluminal shocks in particular may be observable via neutrino and photon fluxes, rather than as protons.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
