标题： 随时间变化的喷流无线电发射 显示英文标题

标题： Time-dependent radio emission from evolving jets

摘要： 我们研究了在外部介质中发射的超音速喷流的时间依赖性辐射和动力学特性，使用了流体动力学模拟和数值辐射转移计算。 这些包括适用于星系和星系外系统的环境介质的各种结构模型。 辐射转移公式充分考虑了发射、吸收、再发射、法拉第旋转和法拉第转换。 生成了高时间分辨率的强度图，逐帧跟踪演化的喷流的空间流体动力学和辐射特性。 通过在发射图上进行空间积分计算了强度光曲线。 我们将这些模型应用于活动星系核（AGN）中的喷流。 从喷流模拟和时间依赖性发射计算中，我们得出了不同演化阶段喷流的发射强度和大小的经验关系。 喷流发射的时间特性不仅仅是喷流本身流体力学和热力学性质变化的结果。 它们还取决于喷流与周围介质之间的相互作用。 因此，对射电喷流形态的解释需要考虑环境因素。 我们的计算还表明，环境相互作用可以影响特定的发射特征，例如内部激波和热点。 对这些明亮特征的时间演化和空间分布进行量化，以及喷流大小与发射之间导出的关系，将使我们能够对AGN的流体力学和周围介质的结构施加限制。 显示英文摘要

摘要： We investigated the time-dependent radiative and dynamical properties of light supersonic jets launched into an external medium, using hydrodynamic simulations and numerical radiative transfer calculations. These involved various structural models for the ambient media, with density profiles appropriate for galactic and extragalactic systems. The radiative transfer formulation took full account of emission, absorption, re-emission, Faraday rotation and Faraday conversion explicitly. High time-resolution intensity maps were generated, frame-by-frame, to track the spatial hydrodynamical and radiative properties of the evolving jets. Intensity light curves were computed via integrating spatially over the emission maps. We apply the models to jets in active galactic nuclei (AGN). From the jet simulations and the time-dependent emission calculations we derived empirical relations for the emission intensity and size for jets at various evolutionary stages. The temporal properties of jet emission are not solely consequences of intrinsic variations in the hydrodynamics and thermal properties of the jet. They also depend on the interaction between the jet and the ambient medium. The interpretation of radio jet morphology therefore needs to take account of environmental factors. Our calculations have also shown that the environmental interactions can affect specific emitting features, such as internal shocks and hotspots. Quantification of the temporal evolution and spatial distribution of these bright features, together with the derived relations between jet size and emission, would enable us to set constraints on the hydrodynamics of AGN and the structure of the ambient medium.