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arXiv 0709.3838astro-ph
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相对论性两分量喷流的横向稳定性

Transverse stability of relativistic two-component jets

Z. Meliani, R. Keppens

摘要:

背景:来自不同来源的天体物理喷流似乎是分层的,有一个快速的内部喷流和一个较慢的外部喷流。由于每个部件的发射机制可能不同,因此它们的界面将产生不同的旋转,而外部射流半径表示可能发生中断的第二界面。目的:我们探讨分层,旋转,相对论性的两个组成部分的射流,反过来嵌入静态星际介质的稳定性。研究方法:利用AMRVAC网格自适应相对论流体动力学模拟程序,研究了二元相对论射流的非线性方位稳定性。我们模拟直到完成多次内部射流旋转。结果如下:我们发现的证据扩展的剪切流层之间的两个射流组件的发展,导致在内部射流,开尔文-亥姆霍兹表面模式在其原始接口的增长模式,和他们的非线性相互作用。这两种波模式都是由声波激发的,声波在对称轴和两个射流部件的界面之间反射。它们的相互作用诱导剪切流层外缘处的近静止、反向旋转涡的增长。一个沉重的外部射流的存在允许减缓他们的进一步发展,并保持准直流。在喷流的外边界,小尺度的瑞利-泰勒不稳定性的发展,而不破坏喷流的配置。结论:我们证明了具有重冷外部喷流的双组分相对论喷流的横截面是非线性稳定的。

英文摘要:

Context: Astrophysical jets from various sources seem to be stratified, with a fast inner jet and a slower outer jet. As it is likely that the launching mechanism for each component is different, their interface will develop differential rotation, while the outer jet radius represents a second interface where disruptions may occur. Aims: We explore the stability of stratified, rotating, relativistic two-component jets, in turn embedded in static interstellar medium. Methods: In a grid-adaptive relativistic hydrodynamic simulation with the AMRVAC code, the non-linear azimuthal stability of two-component relativistic jets is investigated. We simulate until multiple inner jet rotations have been completed. Results: We find evidence for the development of an extended shear flow layer between the two jet components, resulting from the growth of a body mode in the inner jet, Kelvin-Helmholtz surface modes at their original interface, and their nonlinear interaction. Both wave modes are excited by acoustic waves which are reflected between the symmetry axis and the interface of the two jet components. Their interaction induces the growth of near stationary, counterrotating vortices at the outer edge of the shear flow layer. The presence of a heavy external jet allows to slow down their further development, and maintain a collimated flow. At the outer jet boundary, small-scale Rayleigh-Taylor instabilities develop, without disrupting the jet configuration. Conclusion: We demonstrate that the cross-section of two-component relativistic jets, with a heavy, cold outer jet, is non-linearly stable.

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