Comparative study between N-body and Fokker–Planck simulations for rotating star clusters – II. Two-component models
Comparative study between N-body and Fokker–Planck simulations for rotating star clusters – II. Two-component models
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DOI：
10.1093/mnras/stt099
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发表时间：
2012-11
影响因子：
4.8
通讯作者：
Jongsuk Hong;Eunhyeuk Kim;Hyung-Mok Lee;R. Spurzem
中科院分区：
文献类型：
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作者：
Jongsuk Hong;Eunhyeuk Kim;Hyung-Mok Lee;R. Spurzem
为了了解初始转动对具有质量谱的潮汐限制星系团演化的影响，我们对具有不同初始转动的星系团进行了N体模拟，并将模拟结果与Fokker-Planck（FP）模拟结果进行了比较.我们证实了团簇的演化不仅受到初始旋转的加速，而且还受到质量谱的加速。对于慢转模型，N体模型和FP模型的质量、能量和角动量随时间的演化具有很好的一致性。另一方面，对于快速旋转的模型，由于N体模拟中杆不稳定性的发展，在演化的早期阶段这两种方法之间存在显着差异。N体模拟的团簇形状变成三轴甚至扁长，这是二维FP模拟不能产生的。团簇的总角动量和总质量迅速减小，而棒状结构持续存在。当转动能小于杆不稳定的临界值时，团簇的形状又变为近轴对称，并遵循FP方程预测的演化轨迹。我们再次证实，当M2/M1（m2>/m1）^（3/2）> 0.16时，能量均衡并未完全实现。通过研究每个质量分量的角动量，我们发现不同质量分量之间的角动量交换发生，类似于导致均分的能量交换。
To understand the effects of the initial rotation on the evolution of the tidally limited clusters with mass spectrum, we have performed N-body simulations of the clusters with different initial rotations and compared the results with those of the Fokker-Planck (FP) simulations. We confirmed that the cluster evolution is accelerated by not only the initial rotation but also the mass spectrum. For the slowly rotating models, the time evolutions of mass, energy and angular momentum show good agreements between N-body and FP simulations. On the other hand, for the rapidly rotating models, there are significant differences between these two approaches at the early stage of the evolutions because of the development of bar instability in N-body simulations. The shape of the cluster for N-body simulations becomes tri-axial or even prolate, which cannot be produced by the 2-dimensional FP simulations. The total angular momentum and the total mass of the cluster decrease rapidly while bar-like structure persists. After the rotational energy becomes smaller than the critical value for the bar instability, the shape of the cluster becomes nearly axisymmetric again, and follows the evolutionary track predicted by the FP equation. We have confirmed again that the energy equipartiton is not completely achieved when M2/M1(m2>/m1)^(3/2) > 0.16. By examining the angular momentum at each mass component, we found that the exchange of angular momentum between different mass components occurs, similar to the energy exchange leading to the equipartition.