Rayleigh-Taylor instability in two-component relativistic jets
Rayleigh-Taylor instability in two-component relativistic jets
复制标题
二分量相对论性喷流中的瑞利-泰勒不稳定性
DOI：
10.1093/mnras/stx1770
复制
发表时间：
2017
影响因子：
4.8
通讯作者：
Porth Oliver
中科院分区：
文献类型：
--
作者：
Toma Kenji;Komissarov Serguei S.;Porth Oliver
与活动星系核和伽玛射线爆发相关的相对论性喷流可以在没有明显动量损失的情况下传播很远的距离。同时，它们是明亮的发射器，这表明它们有很强的能量耗散。这指向了一种内部耗散的机制，它不会导致气流的整体中断。一种可能是内部冲击，另一种可能是由局部不稳定造成的动荡。当自由膨胀的射流受到茧或外部气体压力的限制时，就会引发这种不稳定性。本文采用二维计算机模拟的方法研究了双组分脊鞘流体动力射流与外界气体进入压力平衡时的动力学特性。我们发现射流振荡导致瑞利-泰勒型不稳定性的快速发生，这导致了额外的内部耗散和射流成分的混合。尽管在细节上略有不同，但这一结果适用于重棘-轻鞘和轻棘-重鞘构型。这一结果可能为某些AGN喷流在kpc尺度上的空间耀斑现象提供解释。
Relativistic jets associated with active galactic nuclei and gamma-ray bursts propagate over huge distances without significant loss of momentum. At the same time they are bright emitters, which is indicative of strong energy dissipation. This points towards a mechanism of internal dissipation which does not result in a global disruption of the flow. One possibility is internal shocks and another one is turbulence driven by local instabilities. Such instabilities can be triggered when a freely expanding jet is reconfined by either the cocoon or external gas pressure. In this paper, we study the dynamics of two-component spine-sheath hydrodynamic jets coming into pressure equilibrium with external gas using 2D computer simulations. We find that the jet oscillations lead to a rapid onset of Rayleigh–Taylor-type instabilities, which results in additional internal dissipation and mixing of the jet components. Although slightly different in details, this outcome holds both for the heavy-spine-light-sheath and light-spine-heavy-sheath configurations. The results may provide an explanation to the spatial flaring observed in some AGN jets on kpc-scales.