N体模拟的多质量球结构模型
Multimass spherical structure models for N-body simulations
摘要：
本文提出了一种简单有效的方法，利用多质量技术建立N体模拟的球形结构模型。与单质量模型相比，这种技术大大减少了解析给定比例所需的计算机运行时间。因此，它允许解决较小的尺度在N体模拟给定的计算机运行时间。在这里，我们提出了几个模型，其有效分辨率高达1.68 × 10^9个粒子，它们的维里半径在宇宙学相关的时间尺度上是稳定的。作为一个应用，我们证实了Dehnen（2005）的理论预测，即在无碰撞结构（如暗物质晕）的合并中，最陡祖先的尖点总是被保留下来的。我们用大约10^8个粒子的有效粒子数来模拟每个合并的祖先。我们还发现，在一个核心的核心合并的中心密度大约增加了一倍，而在尖点尖点的情况下，中心密度只增加了约50%。这可能表明，通过合并过程，平板结构的中心区域得到更好的保护并且获得更少的能量输入。
英文摘要：
We present a simple and efficient method to set up spherical structure models for N-body simulations with a multimass technique. This technique reduces by a substantial factor the computer run time needed in order to resolve a given scale as compared to single-mass models. It therefore allows to resolve smaller scales in N-body simulations for a given computer run time. Here, we present several models with an effective resolution of up to 1.68 x 10^9 particles within their virial radius which are stable over cosmologically relevant time-scales. As an application, we confirm the theoretical prediction by Dehnen (2005) that in mergers of collisonless structures like dark matter haloes always the cusp of the steepest progenitor is preserved. We model each merger progenitor with an effective number of particles of approximately 10^8 particles. We also find that in a core-core merger the central density approximately doubles whereas in the cusp-cusp case the central density only increases by approximately 50%. This may suggest that the central region of flat structures are better protected and get less energy input through the merger process.
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