Footprints of the Sagittarius dwarf galaxy in the Gaia data set
Footprints of the Sagittarius dwarf galaxy in the Gaia data set
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DOI：
10.1093/mnras/stz583
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发表时间：
2018-08
影响因子：
4.8
通讯作者：
C. Laporte;I. Minchev;K. Johnston;F. G'omez
中科院分区：
文献类型：
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作者：
C. Laporte;I. Minchev;K. Johnston;F. G'omez
我们分析了银河系（MW）与类似人马座的dSph （Sgr）相互作用的n体模拟，根据盖亚DR2的发现，寻找可能归因于其在太阳周围相空间体积中的轨道历史的特征。Sgr的反复影响激发了圆盘中耦合的垂直和径向振荡，这些振荡定性地，并在很大程度上定量地能够再现6D Gaia DR2样品中的许多特征，从中位数VR， vφ， V$z$速度图到局部δρ($ V$z$, $z$)相空间螺旋，这是在给定体积内对耦合振荡的全局圆盘响应的表现。大尺度速度场的模式很好地描述了由Sgr撞击激发的紧密缠绕的螺旋和垂直波纹。我们表明，Sgr的最后一次近中心通道重置了局部现今δρ($v$ z$, $z$)螺旋的形成，并将其形成位置定位在500-800 Myr左右。正如预期的那样，δρ(vz, $z$)在Gaia DR2数据和模拟中作为半径的函数而增大和减小。这是第一个能够在不同尺度上解释数据中如此多特征的n体模型。我们演示了如何利用银河系盘的全部范围来确定从Myr到Gyr的扰动日期，探测潜在的潜力并约束Sgr的质量损失历史。δρ(vz, $z$)在所有恒星群中看起来都是一样的，直到最年轻的年龄，这就排除了条形屈曲起源的可能性。
We analyse an N-body simulation of the interaction of the Milky Way (MW) with a Sagittarius-like dSph (Sgr), looking for signatures which may be attributed to its orbital history in the phase space volume around the Sun in light of Gaia DR2 discoveries. The repeated impacts of Sgr excite coupled vertical and radial oscillations in the disc which qualitatively, and to a large degree quantitatively are able to reproduce many features in the 6D Gaia DR2 samples, from the median VR, Vϕ, V$z$ velocity maps to the local δρ($v$$z$, $z$) phase-space spiral which is a manifestation of the global disc response to coupled oscillations within a given volume. The patterns in the large-scale velocity field are well described by tightly wound spirals and vertical corrugations excited from Sgr’s impacts. We show that the last pericentric passage of Sgr resets the formation of the local present-day δρ($v$$z$, $z$) spiral and situate its formation around 500-800 Myr. As expected δρ(vz, $z$) grows in size and decreases in woundedness as a function of radius in both the Gaia DR2 data and simulations. This is the first N-body model able to explain so many of the features in the data on different scales. We demonstrate how to use the full extent of the Galactic disc to date perturbations dating from Myr to Gyr, probe the underlying potential and constrain the mass-loss history of Sgr. δρ(vz, $z$) looks the same in all stellar populations age bins down to the youngest ages which rules out a bar buckling origin.