Numerically calibrated model for propagation of a relativistic unmagnetized jet in dense media
Numerically calibrated model for propagation of a relativistic unmagnetized jet in dense media
复制标题
相对论性非磁化射流在致密介质中传播的数值校准模型
DOI：
10.1093/mnras/sty760
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发表时间：
2017
影响因子：
4.8
通讯作者：
E. Nakar
中科院分区：
文献类型：
--
作者：
R. Harrison;O. Gottlieb;E. Nakar
相对论性喷流存在于各种尺度的高能天体物理系统中。它们与周围介质的相互作用至关重要，因为它决定了射流的演变、可观测的特征和对环境的反馈。在运动过程中，射流与周围介质的相互作用形成了一个高压茧，在一定条件下，这个茧会对射流进行准直并强烈影响其传播。最近，Bromberg等人（2011）导出了一种一般简化（半）解析解，用于在具有一系列密度分布的介质中传播的非磁化射流和茧的演化。在这项工作中，我们使用了大量的二维和三维相对论流体动力学模拟来测试该模型的有效性和准确性。我们讨论了解析模型和数值模拟之间的异同，也在某种程度上讨论了二维和三维模拟之间的异同。我们的主要发现是，虽然分析模型是高度简化的，但它正确地预测了喷气茧系统主要成分的演变，包括其时间演变和各种状态之间的过渡（例如，准直到非准直）。解析解预测的射流头速度比模拟快了约3倍，只要头速度是牛顿速度。我们利用模拟结果对分析模型进行了校正，大大提高了分析模型的精度。我们提供了一个applet，它可以半解析地计算用户在此http URL上定义的任意密度配置文件中的射流传播
Relativistic jets reside in high-energy astrophysical systems of all scales. Their interaction with the surrounding media is critical as it determines the jet evolution, observable signature, and feedback on the environment. During its motion the interaction of the jet with the ambient media inflates a highly pressurized cocoon, which under certain conditions collimates the jet and strongly affects its propagation. Recently, Bromberg et al. (2011) derived a general simplified (semi)analytic solution for the evolution of the jet and the cocoon in case of an unmagnetized jet that propagates in a medium with a range of density profiles. In this work we use a large suite of 2D and 3D relativistic hydrodynamic simulations in order to test the validity and accuracy of this model. We discuss the similarities and differences between the analytic model and numerical simulations and also, to some extent, between 2D and 3D simulations. Our main finding is that although the analytic model is highly simplified, it properly predicts the evolution of the main ingredients of the jet-cocoon system, including its temporal evolution and the transition between various regimes (e.g., collimated to uncollimated). The analytic solution predicts a jet head velocity that is faster by a factor of about 3 compared to the simulations, as long as the head velocity is Newtonian. We use the results of the simulations to calibrate the analytic model which significantly increases its accuracy. We provide an applet that calculates semi-analytically the propagation of a jet in an arbitrary density profile defined by the user at this http URL