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arXiv 1608.03441astro-ph.GAastro-ph.CO
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星系团旋臂的潮汐起源

Tidal origin of spiral arms in galaxies orbiting a cluster

Marcin Semczuk, Ewa L. Lokas, Andres del Pino

摘要:

在盘状星系中形成宏伟设计的旋臂的一个场景涉及它们与卫星或另一个星系的相互作用。在这里,我们考虑另一种可能性,扰动是由于潜在的星系团。利用$N$体模拟方法研究了一个围绕室女座星系团旋转的类银河星系中旋臂的形成和演化。该星系被放置在几个不同大小但相似偏心率的轨道上,其演化为10 Gyr。潮汐诱导的,双臂,近似对数的螺旋结构形成的每一个在近心通道。旋臂随着时间的推移而消散和卷起,在下一个近心点通道再次被触发。我们通过分析俯仰角和臂强度的时间演变来确认这种瞬态和经常性的武器。我们发现,最强的手臂是在最紧的轨道上形成的,但他们很快就结束了,并受到另一个近心通道的干扰。我们更详细地分析了最长轨道上的臂,它们慢慢地结束,并存活了最长的时间。对旋臂的速度分布的测量表明它们是运动学密度波。我们试图通过选择室女星系团中的大设计螺旋星系与观测进行比较。在这些例子中,我们发现了9个例子,它们没有最近互动的迹象,也没有同伴的存在。对于其中三个,我们提出了密切的结构类似物在我们模拟的螺旋星系。

英文摘要:

One of the scenarios for the formation of grand-design spiral arms in disky galaxies involves their interactions with a satellite or another galaxy. Here we consider another possibility, where the perturbation is instead due to the potential of a galaxy cluster. Using $N$-body simulations we investigate the formation and evolution of spiral arms in a Milky Way-like galaxy orbiting a Virgo-like cluster. The galaxy is placed on a few orbits of different size but similar eccentricity and its evolution is followed for 10 Gyr. The tidally induced, two-armed, approximately logarithmic spiral structure forms on each of them during the pericenter passages. The spiral arms dissipate and wind up with time, to be triggered again at the next pericenter passage. We confirm this transient and recurrent nature of the arms by analyzing the time evolution of the pitch angle and the arm strength. We find that the strongest arms are formed on the tightest orbit, however they wind up rather quickly and are disturbed by another pericenter passage. The arms on the most extended orbit, which we analyze in more detail, wind up slowly and survive for the longest time. Measurements of the pattern speed of the arms indicate that they are kinematic density waves. We attempt a comparison with observations by selecting grand-design spiral galaxies in the Virgo cluster. Among those, we find nine examples bearing no signs of recent interactions or the presence of companions. For three of them we present close structural analogues among our simulated spiral galaxies.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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