Polar ring galaxies as tests of gravity
Polar ring galaxies as tests of gravity
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DOI：
10.1093/mnras/stt639
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发表时间：
2013-04
影响因子：
4.8
通讯作者：
F. Lüghausen;B. Famaey;P. Kroupa;G. Angus;Francoise Combes;Gianfranco Gentile;Gianfranco Gentile;O. Tiret;Hongsheng Zhao
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文献类型：
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作者：
F. Lüghausen;B. Famaey;P. Kroupa;G. Angus;Francoise Combes;Gianfranco Gentile;Gianfranco Gentile;O. Tiret;Hongsheng Zhao
极环星系是研究星系引力位三维形状的理想对象，因为它可以在两个垂直的平面上测量两条自转曲线。观测研究系统地揭示了扩展的极环中的自转速度比相关的宿主星系中的自转速度大。在暗物质的背景下，这只能通过沿着极环沿着系统地变平的暗晕来解释。在这里，我们指出，这些物体也可以作为非常有效的引力理论的测试，如基于Milgromian动力学（也称为修正的牛顿动力学或MOND）。我们运行一组极环模型，使用Milgromian和牛顿动力学来预测两个平面中旋转曲线的预期形状，改变系统的总质量，环相对于主机的质量和环中心孔的大小。我们发现，Milgromian动力学不仅自然地导致旋转速度通常在扩展的极环中比在主机中更高，就像在没有暗物质的牛顿动力学中一样，而且它还得到了正确的速度形状和幅度。因此，米尔格罗米动力学充分解释了极环星系的这一特殊性质。
Polar ring galaxies are ideal objects with which to study the three-dimensional shapes of galactic gravitational potentials since two rotation curves can be measured in two perpendicular planes. Observational studies have uncovered systematically larger rotation velocities in the extended polar rings than in the associated host galaxies. In the dark matter context, this can only be explained through dark haloes that are systematically flattened along the polar rings. Here, we point out that these objects can also be used as very effective tests of gravity theories, such as those based on Milgromian dynamics (also known as Modified Newtonian Dynamics or MOND). We run a set of polar ring models using both Milgromian and Newtonian dynamics to predict the expected shapes of the rotation curves in both planes, varying the total mass of the system, the mass of the ring with respect to the host and the size of the hole at the centre of the ring. We find that Milgromian dynamics not only naturally leads to rotation velocities being typically higher in the extended polar rings than in the hosts, as would be the case in Newtonian dynamics without dark matter, but that it also gets the shape and amplitude of velocities correct. Milgromian dynamics thus adequately explains this particular property of polar ring galaxies.