Slowly breaking waves: the longevity of tidally induced spiral structure
Slowly breaking waves: the longevity of tidally induced spiral structure
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缓慢破碎的波浪：潮汐引起的螺旋结构的长寿
DOI：
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
Jeong
中科院分区：
文献类型：
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作者：
C. Struck;C. Dobbs;Jeong
我们在两组快速（边缘束缚或非束缚）飞越星系碰撞的数值模型中发现了长寿命波，这两组模型是用两种不同的代码独立执行的。在这两个模拟集中，螺旋都不是碰撞引起的条形形成的结果。尽管波浪的外观随时间而变化，但它们不会像文献中描述的其他情况那样反复消失和重新形成。我们还提出了一种分析理论，可以解释波结构，而不是传播瞬态，也不是通过圆盘传播的固定模式。当这些波通过圆盘传播时，它们由脉冲扰动引发的相干振荡维持。具体来说，解析理论表明它们是扰动后追求相关周转轨道的恒星群中的焦散波。该理论是斯特鲁克及其合作者针对碰撞环星系开发的理论的延伸。这些模型表明，这种类型的波可能会持续几个吉里，并且星系相互作用发生在相当的时间尺度上，因此该机制产生的波可以在观测到的螺旋中得到很好的体现。特别是，这种机制可以解释在一些附近的早期型星系中看到的紧密缠绕且可能寿命较长的螺旋。这些螺旋也可能在星系团和星系团中很常见，在这些星系团和星系团中，星系之间的快速相遇相对频繁地发生。然而，随着螺旋变得紧密缠绕，并演化到适度的幅度，除非它们在附近，否则可能很难解决。尽管如此，这种效应可能是由星系骚扰引起的几个过程之一，并且通过波增强的恒星形成，促成了布彻-奥姆勒效应。
We have discovered long-lived waves in two sets of numerical models of fast (marginally bound or unbound) flyby galaxy collisions, carried out independently with two different codes. In neither simulation set are the spirals the result of a collision-induced bar formation. Although there is variation in the appearance of the waves with time, they do not disappear and reform recurrently, as seen in other cases described in the literature. We also present an analytic theory that can account for the wave structure, not as propagating transients, nor as a fixed pattern propagating through the disc. While these waves propagate through the disc, they are mantained by the coherent oscillations initiated by the impulsive disturbance. Specifically, the analytic theory suggests that they are caustic waves in ensembles of stars pursuing correlated epicyclic orbits after the disturbance. This theory is an extension of that developed by Struck and collaborators for colliding ring galaxies. The models suggest that this type of wave may persist for a couple of Gyr, and galaxy interactions occur on comparable time-scales, so waves produced by the mechanism may be well represented in observed spirals. In particular, this mechanism can account for the tightly wound, and presumably long-lived, spirals seen in some nearby early-type galaxies. These spirals are also likely to be common in groups and clusters, where fast encounters between galaxies occur relatively frequently. However, as the spirals become tightly wound, and evolve to modest amplitudes, they may be difficult to resolve unless they are nearby. None the less, the effect may be one of several processes that result from galaxy harassment, and via wave-enhanced star formation, contributes to the Butcher–Oemler effect.
通过测量图案速度的径向变化来揭示螺旋结构的起源
DOI：
10.1088/0004-637x/702/1/277
发表时间：
2009
期刊：
The Astrophysical Journal
影响因子：
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作者：
Meidt S
通讯作者：
Meidt S