论文标题
螺旋不稳定性：模式饱和度和衰减
Spiral instabilities: Mode saturation and decay
论文作者
论文摘要
本文继续报道了支持螺旋不稳定性的盘式星系模拟行为的不同方面。本文的重点是证明线性螺旋不稳定性如何饱和和衰减，以及光盘的性质如何影响螺旋的限制幅度。再次，我们采用了理想化的模型，每个模型都具有我们遵循的单一不稳定性，直到它运行其路线为止。值得注意的是，我们发现模式的增长率与其限制幅度之间存在密切的相关性，尽管仅来自六个模拟。我们表明，旋转附近的非线性轨道偏转会导致该模式饱和，并且在缓慢增长的模式下可用的时间越多，会在较低的幅度下产生临界偏转。我们还发现，在模式饱和之前，在内部lindblad共振处的散射是微不足道的。我们认为，我们认为我们已经实现的一系列论文的目标一直是为了建立令人信服且有据可查的描述，即对他人和我们自己在模拟中观察到的螺旋模式的物理行为，而我们自己数十年来。理解模拟是朝着更大目标迈出的重要一步，即从星系中找到可以面对确定机制的观察性证据。
This paper continues a series reporting different aspects of the behaviour of disc galaxy simulations that support spiral instabilities. The focus in this paper is to demonstrate how linear spiral instabilities saturate and decay, and how the properties of the disc affect the limiting amplitude of the spirals. Once again, we employ idealized models that each possess a single instability that we follow until it has run its course. Remarkably, we find a tight correlation between the growth rate of the mode and its limiting amplitude, albeit from only six simulations. We show that non-linear orbit deflections near corotation cause the mode to saturate, and that the more time available in a slowly-growing mode creates the critical deflections at lower amplitude. We also find that scattering at the inner Lindblad resonance is insignificant until after the mode has saturated. Our objective in this series of papers, which we believe we have now achieved, has been to develop a convincing and well-documented account of the physical behaviour of the spiral patterns that have been observed in simulations by others, and by ourselves, for many decades. Understanding the simulations is an important step towards the greater objective, which is to find observational evidence from galaxies that could confront the identified mechanism.
