The grazing encounter between IC 2163 and NGC 2207: pushing the limits of observational modelling
The grazing encounter between IC 2163 and NGC 2207: pushing the limits of observational modelling
复制标题
IC 2163 和 NGC 2207 的擦肩而过：突破观测模型的极限
DOI：
10.1111/j.1365-2966.2005.09539.x
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发表时间：
2005
影响因子：
4.8
通讯作者：
Vassar
中科院分区：
文献类型：
--
作者：
C. Struck;M. Kaufman;E. Brinks;M. Thomasson;B. Elmegreen;Debra Meloy Elmegreen Iowa State;Ohio State;U. Hertfordshire;Onsala Space Obs.;I. Watson;Vassar
我们提出了 IC 2163 星系和 NGC 2207 星系之间碰撞的数值流体动力学模型。这些模型扩展了早期工作的结果，即一次对一个星系盘进行建模。我们确认了一般结果，即碰撞主要是平面的，即相对于两个圆盘具有中等倾斜度，对于 IC 2163 来说是顺行的，但对于 NGC 2207 来说是逆行的。我们列出了通过多波段观测发现的各种尺度的 34 个特定形态或运动学特征，我们用它们来约束模型。这些模型能够通过相对轨道重现大部分这些特征，其中伴星盘（IC 2163）首先在西侧侧向滑动主盘（NGC 2207），然后绕着主盘边缘向北移动到东侧的当前位置。这些模型还提供证据表明 NGC 2207 的暗物质晕仅具有中等程度。对于 IC 2163，模型中长时间的顺行扰动会产生潮汐尾，以及与观察到的波形非常相似的椭圆形或眼波形，包括一些精细结构。模型中的逆行扰动在主星系内没有产生强波形。这表明 NGC 2207 中突出的螺旋波在碰撞之前就已经存在，并且在初始条件下施加的波模型证实它们不会被碰撞破坏。通过在主气盘中的初始中心孔和强加的螺旋，该模型还再现了 HI 观测中看到的宽环。模型气盘运动学与观察到的 (HI) 运动学相比较，进一步证实了其有效性。其中包括年轻恒星反馈加热的算法，反馈模型表明大约 250 Myr 前 IC 2163 中发生了中度星暴。我们相信，这是现在最好的碰撞星系建模系统之一，尽管该模型仍然可以通过包含全盘自重力来改进。如此多的个体特征的观测结果和模型之间的对抗提供了对碰撞理论最有力的检验之一。模型的成功证实了这一理论，但实现这一目标所需的努力以及模型对初始条件的敏感性表明，在任何碰撞系统中，很难在小于约千秒差距的尺度上对特定结构进行建模。
We present numerical hydrodynamical models of the collision between the galaxies IC 2163 and NGC 2207. These models extend the results of earlier work where the galaxy discs were modeled one at a time. We confirm the general result that the collision is primarily planar, that is, at moderate inclination relative to the two discs, and prograde for IC 2163, but retrograde for NGC 2207. We list 34 specific morphological or kinematic features on a variety of scales, found with multi-waveband observations, which we use to constrain the models. The models are able to reproduce most of these features, with a relative orbit in which the companion (IC 2163) disc first side-swipes the primary (NGC 2207) disc on the west side, then moves around the edge of the primary disc to the north and to its current position on the east side. The models also provide evidence that the dark matter halo of NGC 2207 has only moderate extent. For IC 2163, the prolonged prograde disturbance in the model produces a tidal tail, and an oval or ocular waveform very much like the observed ones, including some fine structure. The retrograde disturbance in the model produces no strong waveforms within the primary galaxy. This suggests that the prominent spiral waves in NGC 2207 were present before the collision, and models with waves imposed in the initial conditions confirm that they would not be disrupted by the collision. With an initial central hole in the gas disc of the primary, and imposed spirals, the model also reproduces the broad ring seen in HI observations. Model gas disc kinematics compare well to the observed (HI) kinematics, providing further confirmation of its validity. An algorithm for feedback heating from young stars is included, and the feedback models suggest the occurence of a moderate starburst in IC 2163 about 250 Myr ago. We believe that this is now one of the best modeled systems of colliding galaxies, though the model could still be improved by including full disc self-gravity. The confrontation between observations and models of so many individual features provides one of the strongest tests of collision theory. The success of the models affirms this theory, but the effort required to achieve this, and the sensitivity of models to initial conditions, suggests that it will be difficult to model specific structures on scales smaller than about a kiloparsec in any collisional system.