论文标题
磁性相对论流出的反向冲击形成条件：调解理论和模拟
Reverse shock forming condition for magnetized relativistic outflows: reconciling theories and simulations
论文作者
论文摘要
反向冲击（RS）发射可用于探测相对论喷射的特性，尤其是磁化$σ$的程度，在伽马射线爆发（GRB）余气中。但是，文献中关于RS形成的物理状况存在混乱，并且尚不完全了解磁场在RS动力学中的作用在RS动力学中的作用。利用冲击跳跃条件，我们表征了磁化Rs的性能。我们比较了来自不同理论和数值模拟的RS动力学和形成条件，并调和它们之间的差异。严格的RS形成条件被发现为$σ<σ_\ Mathrm {Cr} =（8/3）γ_4^2（N_1/N_4）$，其中$ n_4 $和$ n_1 $是exta的静止数字密度，分别是环境介质，分别是$γ_4$ $γ_4$ lorentz Factic faction fixt faction。 $σ_\ Mathrm {Cr} $是关键的磁化。与以前的主张相反，我们证明这种情况与其他理论和模拟结果一致，这可以进一步应用于未来数值模拟的设置和一致性检查。使用这种条件，我们提出了RS形成的特征半径，并将磁化壳分为三个机制：“厚外壳”（相对论RS），“薄壳”（跨性别的RS）和“无RS”机制。关键的磁化$σ_\ Mathrm {Cr} $通常低于薄外壳的统一，但可能会在“厚外壳”制度中达到$ \ sim 100-1000 $。我们的结果可以应用于以po频率为主导的弹出的动态演化，并具有潜在的应用于磁化相对论流出的自一致的灯曲线建模。
Reverse shock (RS) emission can be used to probe the properties of the relativistic ejecta, especially the degree of magnetization $σ$, in gamma-ray burst (GRB) afterglows. However, there has been confusion in the literature regarding the physical condition for the RS formation, and the role of magnetic fields in the RS dynamics in the Poynting-flux-dominated regime is not fully understood. Exploiting the shock jump conditions, we characterize the properties of a magnetized RS. We compare the RS dynamics and forming conditions from different theories and numerical simulations, and reconcile the discrepancies among them. The strict RS forming condition is found to be $σ< σ_\mathrm{cr}=(8/3)γ_4^2(n_1/n_4)$, where $n_4$ and $n_1$ are the rest-frame number densities of the ejecta and the ambient medium, respectively, $γ_4$ is the bulk Lorentz factor, and $σ_\mathrm{cr}$ is the critical magnetization. Contrary to previous claims, we prove that this condition agrees with other theoretical and simulated results, which can be further applied to the setup and consistency check of future numerical simulations. Using this condition, we propose a characteristic radius for RS formation, and categorize the magnetized shell into three regimes: 'thick shell' (relativistic RS), 'thin shell' (trans-relativistic RS), and 'no RS' regimes. The critical magnetization $σ_\mathrm{cr}$ is generally below unity for thin shells, but can potentially reaches $\sim 100-1000$ in the 'thick shell' regime. Our results could be applied to the dynamical evolution of Poynting-flux-dominated ejecta, with potential applications to self-consistent lightcurve modelling of magnetized relativistic outflows.
