论文标题
检测LMC诱导的银河晕斜率
Detection of the LMC-induced sloshing of the Galactic halo
论文作者
论文摘要
最近的大量研究表明，LMC可能是巨大的，带有光环质量$> 10^{11} m_ \ odot $。拥有如此附近和庞大的邻居的结果是，预计内部银河系将在我们的银河郊区加速（超过$ \ sim 30 $ kpc）。在这项工作中，我们编译了$ \ sim 500 $的样本，远处的恒星光环，$ r _ {\ rm gc}> 50 $ kpc，以检验此假设。这些恒星占天空的很大一部分，从而使恒星光环的全球视野。我们发现，南半球的恒星平均被蓝光升高，而北部的恒星则是红缩的，与预期的，由于LMC而导致内部光环的预期，大部分是向下加速。我们将这些结果与仿真进行比较，并发现信号与$ 1.5 \ times10^{11} m_ \ odot $ lmc的输入一致。我们与\ textit {gaia} dr2交叉匹配我们的恒星样品，发现平均适当的运动尚不足够精确，无法辨别LMC的效果。我们的结果表明，外银道显着超出平衡，LMC对我们的银河系具有重大影响。
A wealth of recent studies have shown that the LMC is likely massive, with a halo mass $>10^{11} M_\odot$. One consequence of having such a nearby and massive neighbour is that the inner Milky Way is expected to be accelerated with respect to our Galaxy's outskirts (beyond $\sim 30$ kpc). In this work we compile a sample of $\sim 500$ stars with radial velocities in the distant stellar halo, $r_{\rm GC}> 50$ kpc, to test this hypothesis. These stars span a large fraction of the sky and thus give a global view of the stellar halo. We find that stars in the Southern hemisphere are on average blueshifted, while stars in the North are redshifted, consistent with the expected, mostly downwards acceleration of the inner halo due to the LMC. We compare these results with simulations and find the signal is consistent with the infall of a $1.5\times10^{11} M_\odot$ LMC. We cross-match our stellar sample with \textit{Gaia} DR2 and find that the mean proper motions are not yet precise enough to discern the LMC's effect. Our results show that the outer Milky Way is significantly out of equilibrium and that the LMC has a substantial effect on our Galaxy.
