The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream
The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream
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DOI：
10.1093/mnras/stz1371
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发表时间：
2019-08-01
影响因子：
4.8
通讯作者：
Sohn, S. T.
中科院分区：
文献类型：
--
作者：
Erkal, D.;Belokurov, V.;Sohn, S. T.
在Koposov等人的一篇论文中，来自盖亚数据发布2的RR Lyrae被用来证明孤儿流中的恒星的速度矢量与流轨迹明显不一致，这表明它受到了来自银河系卫星的巨大引力扰动。我们认为这种不匹配不可能由于任何现实的静态银河系势而产生，然后探索大麦哲伦云（LMC）的扰动效应。我们发现LMC可以精确地产生观测到的运动轨迹不匹配，因此我们使用孤儿流来测量云的质量。我们同时拟合了银河系和LMC的势，并推断LMC的总质量为1.38(-0.24)（+0.27）× 10(11)M（圆点）才能弯曲Orphan stream，这首次表明LMC对银河系轨道结构具有巨大且可测量的影响。这对任何假设示踪剂绕静态银河系运行的技术都具有深远的影响。此外，我们在50kpc内测量银河系的质量为3.80(-0.11)(+0.14)x 10(11)M（圆点）。最后，我们利用这些结果来预测，由于银河系对LMC的反射运动，银河系恒星晕的外围应该表现出一个巨大的向上运动。
In a companion paper by Koposov et al., RR Lyrae from Gaia Data Release 2 are used to demonstrate that stars in the Orphan stream have velocity vectors significantly misaligned with the stream track, suggesting that it has received a large gravitational perturbation from a satellite of theMilkyWay. We argue that such amismatch cannot arise due to any realistic static Milky Way potential and then explore the perturbative effects of the Large Magellanic Cloud (LMC). We find that the LMC can produce precisely, the observed motion-track mismatch and we therefore use the Orphan stream to measure the mass of the Cloud. We simultaneously fit the Milky Way and LMC potentials and infer that a total LMC mass of 1.38(-0.24)(+0.27) x 10(11)M(circle dot) is required to bend the Orphan stream, showing for the first time that the LMC has a large and measurable effect on structures orbiting the Milky Way. This has far-reaching consequences for any technique which assumes that tracers are orbiting a static MilkyWay. Furthermore, we measure the Milky Way mass within 50 kpc to be 3.80(-0.11)(+0.14) x 10(11)M(circle dot). Finally, we use these results to predict that, due to the reflex motion of the Milky Way in response to the LMC, the outskirts of the Milky Way's stellar halo should exhibit a bulk, upwards motion.