论文标题
螺旋不稳定性：线性和非线性效应
Spiral instabilities: Linear and nonlinear effects
论文作者
论文摘要
我们介绍了稳定的圆盘银河系模型中螺旋反应的研究，以使围绕环均匀间隔的扰动质量进行扰动。响应或唤醒的幅度与扰动的质量成正比，我们发现对低质量环的响应在去除时对响应分散 - 通过线性理论预测的行为。较高的质量环通过在主要共振处散射，引起非线性变化，这引起了散射之前缺乏的不稳定性。从不同频率绕行的两个环的单独唤醒图案产生的净响应显然是螺旋状的。当环的质量较低时，模拟的演变既是定性和定量通过两种单独响应的线性叠加来重现的。我们认为，在模拟中显然是由两个或更多稳定旋转模式的叠加引起的瞬态螺旋，每个模式的叠加最佳，每种模式最好用作非平滑光盘的正常模式。
We present a study of the spiral responses in a stable disc galaxy model to co-orbiting perturbing masses that are evenly spaced around rings. The amplitudes of the responses, or wakes, are proportional to the masses of the perturbations, and we find that the response to a low-mass ring disperses when it is removed -- behaviour that is predicted by linear theory. Higher mass rings cause nonlinear changes through scattering at the major resonances, provoking instabilities that were absent before the scattering took place. The separate wake patterns from two rings orbiting at differing frequencies, produce a net response that is an apparently shearing spiral. When the rings have low mass, the evolution of the simulation is both qualitatively and quantitatively reproduced by linear superposition of the two separate responses. We argue that apparently shearing transient spirals in simulations result from the superposition of two or more steadily rotating patterns, each of which is best accounted for as a normal mode of the non-smooth disc.
