The Orbital Histories of Magellanic Satellites Using Gaia DR2 Proper Motions
The Orbital Histories of Magellanic Satellites Using Gaia DR2 Proper Motions
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DOI：
10.3847/1538-4357/ab7b75
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发表时间：
2020-01
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影响因子：
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通讯作者：
E. Patel;N. Kallivayalil;N. Garavito-Camargo;G. Besla;D. Weisz;R. P. van der Marel;M. Boylan-Kolchin-M.-Boylan-Kolc
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作者：
E. Patel;N. Kallivayalil;N. Garavito-Camargo;G. Besla;D. Weisz;R. P. van der Marel;M. Boylan-Kolchin-M.-Boylan-Kolc
随着 Gaia DR2 的发布，现在可以首次测量银河系 (MW) 晕中质量最低、超微弱卫星星系的自行 (PM)。许多这些微弱的卫星被认为是麦哲伦星云（MC）的卫星。利用六维相空间信息，我们计算了 13 颗超微弱卫星和 5 个经典矮球体在组合 MW+LMC+SMC 势中的轨道历史，以确定哪些星系与 MC 动态相关。这 18 个星系分为四类： (i) 至少在围绕 MC 的最后两个连续轨道上与 MC 绑定的长期麦哲伦卫星（Carina 2、Carina 3、Horologium 1、Hydrus 1）； (ii) 最近由 MC 在 < 1 Gyr 之前捕获的麦哲伦卫星（Reticulum 2、Phoenix 2）； (iii) 与 MC 相互作用的 MW 卫星（Sculptor 1、Tucana 3、Segue 1）； (iv) MW 卫星（Aquarius 2、Canes Venatici 2、Crater 2、Draco 1、Draco 2、Hydra 2、Carina、Fornax、Ursa Minor）。报告了一系列 MW 和 LMC 质量的结果。与之前的工作相反，我们发现 Carina、Fornax 和 MC 之间没有动态关联。最后，我们确定 SMC 引力势的增加会影响作为麦哲伦系统成员的卫星的寿命（长期与最近捕获的），但它不会改变麦哲伦卫星的总数。
With the release of Gaia DR2, it is now possible to measure the proper motions (PMs) of the lowest-mass, ultrafaint satellite galaxies in the Milky Way’s (MW) halo for the first time. Many of these faint satellites are posited to have been accreted as satellites of the Magellanic Clouds (MCs). Using their six-dimensional phase-space information, we calculate the orbital histories of 13 ultrafaint satellites and five classical dwarf spheroidals in a combined MW+LMC+SMC potential to determine which galaxies are dynamically associated with the MCs. These 18 galaxies are separated into four classes: (i) long-term Magellanic satellites that have been bound to the MCs for at least the last two consecutive orbits around the MCs (Carina 2, Carina 3, Horologium 1, Hydrus 1); (ii) Magellanic satellites that were recently captured by the MCs < 1 Gyr ago (Reticulum 2, Phoenix 2); (iii) MW satellites that have interacted with the MCs (Sculptor 1, Tucana 3, Segue 1); and (iv) MW satellites (Aquarius 2, Canes Venatici 2, Crater 2, Draco 1, Draco 2, Hydra 2, Carina, Fornax, Ursa Minor). Results are reported for a range of MW and LMC masses. Contrary to previous work, we find no dynamical association between Carina, Fornax, and the MCs. Finally, we determine that the addition of the SMC’s gravitational potential affects the longevity of satellites as members of the Magellanic system (long-term versus recently captured), but it does not change the total number of Magellanic satellites.