Time‐dependent radio emission from evolving jets
Time‐dependent radio emission from evolving jets
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DOI：
10.1111/j.1365-2966.2010.16554.x
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发表时间：
2010-03
影响因子：
4.8
通讯作者：
C. Saxton;Kinwah Wu;Svetlana Korunoska;K. Lee;Kai-yan Lee;N. E. R. S. S. Laboratory-N.-E.-R.-S.-S.-Laboratory-103004036;University College London;D. Sciences;Princeton University;D. Physics;U. O. H. Kong
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作者：
C. Saxton;Kinwah Wu;Svetlana Korunoska;K. Lee;Kai-yan Lee;N. E. R. S. S. Laboratory-N.-E.-R.-S.-S.-Laboratory-103004036;University College London;D. Sciences;Princeton University;D. Physics;U. O. H. Kong
利用流体力学模拟和辐射传递数值计算，研究了发射到外部介质中的轻超声速喷流的含时辐射和动力学特性。这涉及到环境介质的各种结构模型，以及适用于银河系和河外系统的密度分布。辐射传输公式显式地考虑了发射、吸收、再发射、法拉第旋转和法拉第转换。生成了逐帧的高时间分辨率强度图，以跟踪不断演变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来计算强度光曲线。我们将该模型应用于活动星系核(AGN)中的喷流。从喷流模拟和随时间变化的发射计算中，我们得到了不同演化阶段喷流发射强度和尺寸的经验关系式。喷流发射的时间特性不仅仅是喷流的流体动力学和热学性质的内在变化的结果。它们还取决于喷流和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，如内激波和热点。量化这些明亮特征的时间演化和空间分布，以及所导出的喷流大小和发射之间的关系，将使我们能够对活动星系核的流体动力学和环境介质的结构设置约束。
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.