Structures produced by the collision of extragalactic jets with dense clouds
Structures produced by the collision of extragalactic jets with dense clouds
复制标题
河外喷流与稠密云层碰撞产生的结构
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
J. Dunlop
中科院分区：
文献类型：
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作者：
S. Higgins;T. O’brien;J. Dunlop
通过一系列流体动力学模拟，我们研究了几个参数如何影响河外喷流与致密的星系际云之间的碰撞结果。人们常常认为这种碰撞可以解释某些无线电射流的扭曲结构。然而，对该机制的理论研究对于它是否能够真正重现观察结果存在争议。
这些参数是马赫数以及射流和云与环境介质的相对密度。使用简单的处方，我们生成了合成无线电图像，用于与观测结果进行比较。这些表明简单的射流与云的碰撞可能会产生多种结构。我们用几个例子来说明这一点，并检查一个案例的细节。在大多数情况下，我们看不到明显、持续的偏转。轻型喷气式飞机完全受到干扰。最强大的喷流在撞击时会产生一个热点，其亮度超过任何喷流发射，并且会太快地侵蚀云层而无法形成偏转臂。看来需要适度的马赫数和密度对比才能在无线电结构中产生弯曲。这解释了理论研究之间的明显冲突，因为结论是基于这些参数的不同值。环境介质中产生的冲击可能合理地再现观察到的延伸发射线区域与射电轴的对准。
We investigate how several parameters can affect the results of a collision between an extragalactic jet and a dense, intergalactic cloud, through a series of hydrodynamic simulations. Such collisions are often suggested to explain the distorted structures of some radio jets. However, theoretical studies of this mechanism are in conflict over whether it can actually reproduce the observations.
The parameters are the Mach number, and the relative densities of the jet and the cloud to the ambient medium. Using a simple prescription, we have produced synthetic radio images for comparison with observations. These show that a variety of structures may be produced from simple jet–cloud collisions. We illustrate this with a few examples, and examine the details in one case. In most cases we do not see a clear, sustained deflection. Lighter jets are completely disrupted. The most powerful jets produce a hotspot at the impact which outshines any jet emission, and erode the cloud too quickly to develop a deflected arm. It appears that moderate Mach numbers and density contrasts are needed to produce bends in the radio structure. This explains the apparent conflict between theoretical studies, as conclusions were based on different values of these parameters. Shocks are produced in the ambient medium that might plausibly reproduce the observed alignment of the extended emission-line regions with the radio axis.