Declining rotation curves of galaxies as a test of gravitational theory
Declining rotation curves of galaxies as a test of gravitational theory
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DOI：
10.1093/mnras/stw573
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发表时间：
2016-03
影响因子：
4.8
通讯作者：
H. Haghi;A. Bazkiaei;A. H. Zonoozi;P. Kroupa
中科院分区：
文献类型：
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作者：
H. Haghi;A. Bazkiaei;A. H. Zonoozi;P. Kroupa
与牛顿动力学不同，牛顿动力学是线性的，遵循强等价原理，在任何非线性引力中，如Milgromian动力学(MOND)，都违反了等价原理的强版本，系统的引力动力学受到其所在的外部引力场的影响。这种所谓的外场效应(EFE)是MOND的重要含义之一，并为检验Milgromian动力学提供了一个特殊的背景。在这里，我们研究了18个螺旋星系的自转曲线(RCS)，发现它们的形状限制了EFE。结果表明，EFE通过降低RCS外层的速度，成功地修正了Milgromian动力学拟合中80个样本星系的自转速度高估问题。我们对每个星系不可忽略的邻近源的隐含外场和引力场进行了比较，发现在许多情况下，它与EFE在不确定度内是相容的。因此，我们认为，在米尔格罗米尔动力学的框架下，人们可以利用星系的RCS来约束由星系环境产生的引力场。最后，我们表明，考虑EFE比没有考虑EFE的情况下，在恒星布居合成方面的恒星质光比产生了更实际的值。
Unlike Newtonian dynamics which is linear and obeys the strong equivalence principle, in any nonlinear gravitation such as Milgromian dynamics (MOND), the strong version of the equivalence principle is violated and the gravitational dynamics of a system is influenced by the external gravitational field in which it is embedded. This so called External Field Effect (EFE) is one of the important implications of MOND and provides a special context to test Milgromian dynamics. Here, we study the rotation curves (RCs) of 18 spiral galaxies and find that their shapes constrain the EFE. We show that the EFE can successfully remedy the overestimation of rotation velocities in 80\% of the sample galaxies in Milgromian dynamics fits by decreasing the velocity in the outer part of the RCs. We compare the implied external field with the gravitational field for non-negligible nearby sources of each individual galaxy and find that in many cases it is compatible with the EFE within the uncertainties. We therefore argue that in the framework of Milgromian dynamics, one can constrain the gravitational field induced from the environment of galaxies using their RCs. We finally show that taking into account the EFE yields more realistic values for the stellar mass-to-light ratio in terms of stellar population synthesis than the ones implied without the EFE.