球状星团NGC 2419：引力理论的熔炉
The globular cluster NGC 2419: a crucible for theories of gravity
摘要：
本文分析了用Keck/DEIMOS拍摄的球状星团NGC 2419中恒星的运动学数据。结合再分析深HST和斯巴鲁成像数据，这提供了一个准确的光度分布的集群，我们研究了一个大的动力学模型的系统，通过N体模拟检查稳定性的有效性。我们发现，各向同性模型，无论是牛顿或修正牛顿动力学（MOND）被排除了极高的信心。然而，一个简单的Michie模型在牛顿重力与各向异性的速度色散提供了一个很好的代表性的光度分布和运动学。与此相反，与MOND，我们发现，Michie模型，再现光度分布要么过度预测的速度色散的外围集群，如果质量与光的比例是保持在天体物理学的动机值，否则，他们低估了中央速度色散的质量与光的比例是非常小的。我们发现，在MOND最好的米奇模型是一个因素的10000不太可能比牛顿模型，最适合的系统。当我们研究更一般的模型时，通过用马尔可夫链蒙特卡罗方法求解Jeans方程，发现似然比为350。我们用N体模拟验证了当考虑MOND外场效应时，这些结果没有显著差异。如果假设的集群是在动力学平衡，球形，而不是在一个特殊的轨道上，并拥有一个单一的动力学示踪人口常数M/L是正确的，我们的结论是，目前的观测提供了一个非常严峻的挑战MOND。[删节]
英文摘要：
We present the analysis of a kinematic data set of stars in the globular cluster NGC 2419, taken with Keck/DEIMOS. Combined with a reanalysis of deep HST and Subaru imaging data, which provide an accurate luminosity profile of the cluster, we investigate the validity of a large set of dynamical models of the system, which are checked for stability via N-body simulations. We find that isotropic models in either Newtonian or Modified Newtonian Dynamics (MOND) are ruled out with extremely high confidence. However, a simple Michie model in Newtonian gravity with anisotropic velocity dispersion provides an excellent representation of the luminosity profile and kinematics. In contrast, with MOND we find that Michie models that reproduce the luminosity profile either over-predict the velocity dispersion on the outskirts of the cluster if the mass to light ratio is kept at astrophysically-motivated values, or else they under-predict the central velocity dispersion if the mass to light ratio is taken to be very small. We find that the best Michie model in MOND is a factor of 10000 less likely than the Newtonian model that best fits the system. A likelihood ratio of 350 is found when we investigate more general models by solving the Jeans equation with a Markov-Chain Monte Carlo scheme. We verified with N-body simulations that these results are not significantly different when the MOND external field effect is accounted for. If the assumptions that the cluster is in dynamical equilibrium, spherical, not on a peculiar orbit, and possesses a single dynamical tracer population of constant M/L are correct, we conclude that the present observations provide a very severe challenge for MOND. [abridged]
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