LMC对Milky Way卫星运动学的影响：来自运行太阳顶点的线索
The LMC impact on the kinematics of the Milky Way satellites: clues from the running solar apex
摘要：
矮星系为研究银河系和本星系群的演化提供了一个独特的机会。分析运行的太阳能顶点的MW卫星的运动学的基础上，我们发现了一个意想不到的行为的径向速度分布的偶极项作为银河系的距离的函数。附近的卫星（<100 kpc）具有振幅为140-230 km/s的整体运动，而较远的卫星则显示径向速度的各向同性分布。如此强烈的太阳顶点变化无法用卫星的净旋转来解释，因为它需要极高的旋转速率（约970 km/s）。如果我们从我们的样本中排除LMC及其最密切相关的成员，这不会足够强烈地抑制附近卫星的整体运动。尽管如此，我们已经证明，所观察到的MW卫星的特殊运动学可以解释由LMC的第一次下降所造成的扰动。首先，我们“撤销”的摄动的影响，通过整合的MW卫星的轨道向后（向前）与（没有）大规模LMC。看来，在2 × 10 ^{11} Msun LMC的情况下，内晕中太阳顶点的现代特有增强减弱得最厉害。接下来，在MW-LMC相互作用的自洽高分辨率N体模拟中，我们发现太阳的顶点只显示了具有大量角动量的晕粒子的观测行为，与MW卫星的行为相当。
英文摘要：
Dwarf galaxies provide a unique opportunity for studying the evolution of the Milky Way (MW) and the Local Group as a whole. Analysing the running solar apex based on the kinematics of the MW satellites, we discovered an unexpected behaviour of the dipole term of the radial velocity distribution as a function of the galactocentric distance. The nearby satellites (<100 kpc) have a bulk motion with an amplitude of 140-230 km/s while the more distant ones show an isotropic distribution of the radial velocities. Such strong solar apex variations can not be explained by the net rotation of the satellites, as it would require an enormously high rotation rate (~970 km/s). If we exclude the LMC and its most closely related members from our sample, this does not suppress the bulk motion of the nearby satellites strongly enough. Nevertheless, we have demonstrated that the observed peculiar kinematics of the MW satellites can be explained by a perturbation caused by the first infall of the LMC. First, we `undone' the effect of the perturbation by integrating the orbits of the MW satellites backwards (forwards) with (without) massive LMC. It appears that the present-day peculiar enhancement of the solar apex in the inner halo is diminished the most in the case of 2x10^{11} Msun LMC. Next, in self-consistent high-resolution N-body simulations of the MW-LMC interaction, we found that the solar apex shows the observed behaviour only for the halo particles with substantial angular momentum, comparable to that of the MW satellites.
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