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arXiv 1109.4161astro-ph.CO
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斯蒂芬五重奏模型：流体动力学对群体演化的限制

Models of Stephan's Quintet: Hydrodynamic Constraints on the Group's Evolution

Jeong-Sun Hwang, Curtis Struck, Florent Renaud, Philip Appleton

备注：
9 figures (some with reduced resolution) and 1 table. MNRAS in press
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摘要：

我们提出了光滑粒子流体动力学模型的相互作用在紧凑的星系群，斯蒂芬的五重奏。这项工作是Renaud等人早期的无碰撞N体模拟的延伸，在该模拟中，该集团的大尺度恒星形态被模拟为一系列星系-星系相互作用。考虑到热流体动力学效应，我们进一步研究了Stephan五重星系际气体的动力学相互作用历史和演化。这一组的主要特征，如扩展的潮汐特征和组范围的激波，使我们能够合理地约束模型，同时试图再现系统的多个特征。我们发现，重建从NGC 7319延伸到NGC 7320c的两个长尾在两次单独的遭遇中一个接一个是非常困难和不可能的，因为第二次遭遇通常会破坏或扭曲已经产生的潮汐结构。我们的模型表明，这两个长尾可能是由NGC 7319和7320c之间的一次遭遇同时形成的，导致内部尾巴比外部更薄，密度更大。然后，如观察到的那样，尾部也彼此平行地延伸。模型结果支持了NGC 7318 b和NGC 7319 b之间的多波长观测以及NGC 7318 b以北的星暴区所探测到的群级激波是由NGC 7318 b与星系际气体的高速碰撞所触发的观点。我们的模型显示，高速碰撞形成了一个气体桥，桥中的云在撞击后继续相互作用数千万年。这在该区域产生许多小冲击，导致比单一冲击冲击的冷却时间长得多。

英文摘要：

We present smoothed particle hydrodynamic models of the interactions in the compact galaxy group, Stephan's Quintet. This work is extension of the earlier collisionless N-body simulations of Renaud et al. in which the large-scale stellar morphology of the group was modeled with a series of galaxy-galaxy interactions in the simulations. Including thermohydrodynamic effects in this work, we further investigate the dynamical interaction history and evolution of the intergalactic gas of Stephan's Quintet. The major features of the group, such as the extended tidal features and the group-wide shock, enabled us to constrain the models reasonably well, while trying to reproduce multiple features of the system. We found that reconstructing the two long tails extending from NGC 7319 toward NGC 7320c one after the other in two separate encounters is very difficult and unlikely, because the second encounter usually destroys or distorts the already-generated tidal structure. Our models suggest the two long tails may be formed simultaneously from a single encounter between NGC 7319 and 7320c, resulting in a thinner and denser inner tail than the outer one. The tails then also run parallel to each other as observed. The model results support the ideas that the group-wide shock detected in multi-wavelength observations between NGC 7319 and 7318b and the starburst region north of NGC 7318b are triggered by the high-speed collision between NGC 7318b and the intergalactic gas. Our models show that a gas bridge is formed by the high-speed collision and clouds in the bridge continue to interact for some tens of millions of years after the impact. This produces many small shocks in that region, resulting a much longer cooling time than that of a single impact shock.

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