Relativistic magnetized jets, originating near black holes, are observed to exhibit substructured flows. In this study, we present synthetic synchrotron-emission signatures for different lines of sight and frequencies, derived from three-dimensional relativistic magnetohydrodynamic simulations of pc-scale Active Galactic Nuclei jets. These simulations apply different injection nozzles, injecting steady, variable, and precessing jets. Extending our previous study, here, we have developed a bridge to connect jet dynamics and particle acceleration within relativistic shocks with nonthermal radiation dominant in jets. The emission is derived from Lagrangian particles—injected into the jet and following the fluid—accelerated through diffusive shock acceleration and subsequently cooled by emitting energy via synchrotron and inverse-Compton processes. Overall, the different shock structures lead to the formation of numerous localized emission patterns—interpreted as jet knots. These knot patterns can fade or flare, also as a consequence of merging or Doppler boosting, leading to jet variability. We find knots with high-enough pattern speed supposed to be visible as superluminal motion ≲5c. Synchrotron spectra of all jets reveal double-humped structures, reflecting multiple electron populations characterized by the nature of underlying shock and their age. The precessing jet is the most powerful emitter, featuring a spectrum flatter than the steady and the variable jet. The emission, although essentially governed by the acceleration through shocks, depends on the cooling history of the particle as well. Overall, the continuous reacceleration of electrons through shocks along the jet we found is an essential prerequisite for observing extended jet emission over large timescales and length scales.

中文翻译：

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相对论磁流体动力学射流中的粒子。II. 桥接喷流动力学与多波段非热发射特征


观察到起源于黑洞附近的相对论磁化射流表现出亚结构流。在这项研究中，我们提出了不同视线和频率的合成同步加速器发射特征，这些特征来自 pc 级活跃银河核喷流的三维相对论磁流体动力学模拟。这些仿真应用不同的喷射喷嘴，喷射稳态、可变和进动射流。扩展我们之前的研究，在这里，我们开发了一座桥梁，将相对论激波中的喷流动力学和粒子加速度与喷流中占主导地位的非热辐射联系起来。发射来自拉格朗日粒子——注入射流并跟随流体——通过扩散激波加速加速，随后通过同步加速器和逆康普顿过程发射能量来冷却。总体而言，不同的激波结构导致了许多局部发射模式的形成——解释为喷流结。这些结模式可能会褪色或耀斑，这也是合并或多普勒增强的结果，从而导致射流变化。我们发现具有足够高图案速度的结应该以超光速运动 ≲5c 的形式可见。所有射流的同步加速器光谱都揭示了双峰结构，反映了多个电子群，其特征是潜在冲击的性质及其年龄。进动射流是最强大的发射极，其光谱比稳态射流和可变射流更平坦。发射虽然基本上由冲击加速度控制，但也取决于粒子的冷却历史。 总的来说，我们发现，通过沿射流的激波对电子进行连续的再加速是在大时间尺度和长度尺度上观察扩展喷流发射的重要先决条件。