Does the galaxy NGC1052–DF2 falsify Milgromian dynamics?
Does the galaxy NGC1052–DF2 falsify Milgromian dynamics?
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NGC1052-DF2 星系是否伪造了米尔格罗米亚动力学？
DOI：
10.1038/s41586-018-0429-z
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发表时间：
2018
期刊：
影响因子：
64.8
通讯作者：
Jörg Dabringhausen
中科院分区：
文献类型：
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作者：
Pavel Kroupa;Hosein Haghi;Behnam Javanmardi;Akram Hasani Zonoozi;Oliver Müller;Indranil Banik;Xufen Wu;Hongsheng Zhao;Jörg Dabringhausen
当前物理学中的一个巨大挑战是理解所观察到的星系内部动力学是由于暗物质还是由于引力定律的修改。最近，货车Dokkum等人1报道了超弥漫矮星系NGC 1052-DF 2缺乏暗物质，他们声称这将是矛盾的-对于修改的重力理论，如Milgromian动力学（MOND）2，3。然而，NGC 1052-DF 2并不是孤立的，因此如果不适当地考虑来自邻近星系的外部引力场，就无法在MOND中对其内部动力学进行有效的预测。根据Haghi等人4，包括这种外场效应，表明NGC 1052-DF 2与MOND一致。在任何可行的宇宙学模型中，原始和潮汐矮星系都应该存在，当星系相互作用时，它们形成于富含气体的潮汐碎片中。在基于暗物质的标准宇宙学模型中，原始矮星系以暗物质为主，而潮汐矮星系包含很少（如果有的话）暗物质。在MOND-一个经典的引力势理论，可从拉格朗日守恒能量，总动量和角动量2，6-这两种类型的矮星系无法区分。到目前为止，所有已知的矮星系都表现出类似的动力学行为，这可能意味着暗物质模型的证伪。因此，货车多库姆等人1发现一个没有暗物质的星系，将构成对标准暗物质宇宙学模型的重要验证。给定重子物质的密度分布ρ，米氏引力的引力势φ由广义非线性泊松方程6 µ φ ρ/= π a G [（）] 4确定
A great challenge in current physics is to understand whether the observed internal dynamics of galaxies is due to dark matter or to a modification of the law of gravity. Recently, van Dokkum et al. 1 reported that the ultra-diffuse dwarf galaxy NGC1052–DF2 lacks dark matter, and they claimed that this would—paradoxically—be problematic for modified gravity theories such as Milgromian dynamics (MOND) 2, 3. However, NGC1052–DF2 is not isolated, so a valid prediction of its internal dynamics in MOND cannot be made without properly accounting for the external gravitational fields from neighbouring galaxies. Including this external field effect, following Haghi et al. 4, shows that NGC1052–DF2 is consistent with MOND. In any viable cosmological model, both primordial and tidal dwarf galaxies, which form in gas-rich tidal debris when galaxies interact, should exist. Within the standard dark-matter-based cosmological model, primordial dwarfs are dark-matter-dominated, whereas tidal dwarf galaxies contain very little (if any) dark matter 5. In MOND—a classical potential theory of gravity, derivable from a Lagrangian with conserved energy, total momentum and angular momentum 2, 6—the two types of dwarf galaxies cannot be distinguished. Until now, all known dwarf galaxies have shown similar dynamic behaviour, possibly implying falsification of the dark-matter models 7. The discovery by van Dokkum et al. 1 of a galaxy lacking dark matter would thus constitute an important verification of the standard dark-matter cosmological model. Given the density distribution of baryonic matter, ρ, the gravitational potential of Milgromian gravitation, φ, is determined by the generalized nonlinear Poisson equation 6∣∣ µ φ φ ρ∇∇∇⋅/= π a G [()] 4