论文标题
银河系的北/南不对称：可能连接到垂直相蜗牛
The North/South Asymmetry of the Galaxy: Possible Connection to the Vertical Phase Space Snail
论文作者
论文摘要
根据北/南/南（N/S）不对称的最新发现和相混合特征，例如垂直相空间中的相位螺旋（Snail）结构（$ z-v_ {z {z {z} $），因此发现星系处于不平衡状态。我们表明，矮人示踪剂种群中的N/S不对称性可以用简单的相蜗牛模型进行定量建模，该模型叠加在光滑的平衡背景上。随着相蜗牛与$ z $轴相交，数字密度得到增强，并且相对于银河平面的另一侧，速度分散（$σ_{z} $）被减少。仅适用于观察到的不对称的N/S $σ_{Z} $配置文件，我们获得了相位空间蜗牛的合理参数，尽管模型对潜在参数的复杂依赖性以及数据的显着选择效果，但在建模背景中使用的电位。我们最佳拟合模型给出的蜗牛形状和N/S数密度差都与先前的观察结果一致。平衡背景意味着$ 0.0151^{+0.0050} _ { - 0.0051} $ $ $ {\ rm m} _ {\ odot} \，{\ rm pc}^{ - 3} $的本地暗物质密度为$ 0.0151^{+0.0050} _ { - 0.0051} $ $ {\ rm M} _ {\ odot} \，{\ rm PC}^{ - 3} $。我们模型的垂直体积运动类似于观察，但是带有$ \ sim $ 1.2 $ \ rm km \，s^{ - 1} $ shift。我们的工作证明了相空间蜗牛与N/S不对称性之间的密切相关性。未来的观察性约束将促进更全面的蜗牛模型，以揭示蜗牛功能中编码的银河系潜力和扰动历史。
The Galaxy is found to be in disequilibrium based on recent findings of the North/South (N/S) asymmetry and the phase mixing signatures, such as a phase spiral (snail) structure in the vertical phase space ($z-V_{z}$). We show that the N/S asymmetry in a tracer population of dwarfs may be quantitatively modeled with a simple phase snail model superimposed on a smooth equilibrium background. As the phase snail intersects with the $z$ axis, the number density is enhanced, and the velocity dispersion ($σ_{z}$) is decreased relative to the other side of the Galactic plane. Fitting only to the observed asymmetric N/S $σ_{z}$ profiles, we obtain reasonable parameters for the phase space snail and the potential utilized in modeling the background, despite the complex dependence of the model on the potential parameters and the significant selection effects of the data. Both the snail shape and the N/S number density difference given by our best-fit model are consistent with previous observations. The equilibrium background implies a local dark matter density of $0.0151^{+0.0050}_{-0.0051}$ ${\rm M}_{\odot}\,{\rm pc}^{-3}$. The vertical bulk motion of our model is similar to the observation, but with a $\sim$1.2 $\rm km\,s^{-1}$ shift. Our work demonstrates the strong correlation between the phase space snail and the N/S asymmetry. Future observational constraints will facilitate more comprehensive snail models to unravel the Milky Way potential and the perturbation history encoded in the snail feature.
