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arXiv 1404.2202astro-ph.GA
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MOND外场对球状星团动力学的影响:一般考虑和对NGC 2419的应用

The MOND External Field Effect on the Dynamics of the Globular Clusters: General Considerations and Application to NGC 2419

Kamran Derakhshani

摘要:

本文在修正的牛顿动力学(MOND)框架下研究了外场对球状星团(GC)表面亮度和速度色散分布的影响。使用N-MODY,这是一个N-体模拟代码与MOND潜在的求解器,我们表明,一般的影响扩散集群,服从MOND在其大部分地区的外部场,是它推动的动力学向牛顿政权。另一方面,对于内部基本上是牛顿流体的更紧密的团簇,外场主要在紧密团簇的外部有效。作为一个案例研究,我们选择了遥远的银河系GC NGC 2419。通过改变星团质量、半光半径和质光比,我们的目标是找到一个模型,使用N-MODY最有效地再现观测数据。我们发现,即使我们考虑到银河系的外部场,牛顿普卢默球表示的观测数据比MOND的数量级总$χ^2$的表面亮度和速度色散。

英文摘要:

In this paper, we investigate the external field effect in the context of the MOdified Newtonian Dynamics (MOND) on the surface brightness and velocity dispersion profiles of globular clusters (GCs). Using N-MODY, which is an N-body simulation code with a MOND potential solver, we show that the general effect of the external field for diffuse clusters, which obey MOND in most of their parts, is that it pushes the dynamics towards the Newtonian regime. On the other hand, for more compact clusters, which are essentially Newtonian in their inner parts, the external field is effective mainly in the outer parts of compact clusters. As a case study, we then choose the remote Galactic GC NGC 2419. By varying the cluster mass, half-light radius, and mass-to-light ratio we aim to find a model that will reproduce the observational data most effectively, using N-MODY. We find that even if we take the Galactic external field into account, a Newtonian Plummer sphere represents the observational data better than MOND to an order of magnitude in terms of the total $χ^2$ of surface brightness and velocity dispersion.

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