本地暗物质密度与速度分布研究

暗物质粒子探测实验是粒子物理与天文学的前沿领域。在暗物质粒子直接探测实验中，本地暗物质密度和速度分布是重要的输入参数，从天文学上获取独立的测量有助于减少实验中的参数简并性。最新研究发现银河系可能并非处于平衡态，这对以前的平衡态下动力学研究，包括本地暗物质密度测量，提出了新的挑战。.本课题中，我们将首先聚焦于理解银盘南北不对称的起源，同时在动力学模型中引入非平衡态的成份，以获得更为准确的暗物质密度测量。我们将在相空间把示踪星族分解为平滑背景和螺旋波纹结构，以重构出观测上非对称的南北速度弥散轮廓。另一方面，我们会挑选具有更大空间范围的巨星样本，用Jeans方程从恒星运动学中推导物质密度分布，以获得更加精确和相对独立的暗物质密度测量。此外，我们拟从恒星金属丰度和速度分布中，提取能够示踪暗物质速度分布的恒星成份，以推导本地暗物质速度分布，为暗物质探测实验提供天文学输入参数。

Dark matter particle detection experiment is the frontier of particle physics and astronomy. In direct detection experiments, the local dark matter density and velocity distribution are important input parameters. Independent measurements of the two parameters via astrophysical methods are helpful to decrease the parameter degeneracy in dark matter experiments. The latest studies show that our Milky Way is not in equilibrium, posing a challenge to the previous studies on the dynamical studies under equilibrium state, including the measurements of the local dark matter density..In this proposal, we will first focus on solving the problem of the North-South asymmetry with respect to the Galactic disc. At the same time, we will try to introduce the non-equilibrium component into the dynamical model, in order to obtain more accurate dark matter density measurement. We will decompose the tracer population into a smooth background and a phase space spiral in the phase space, for recovering the asymmetric northern and southern velocity dispersion profiles in observations. On the other hand, we will select a sample of giant stars, which has a larger vertical range. We will apply the vertical Jeans equation to derive the mass distribution from stellar kinematics. This could provide more accurate and relatively independent measurement of the dark matter density. Besides, from the stellar distribution in the metallicity and velocity plane, we will extract the stellar components which can trace the velocity distribution of dark matter. This can help to derive the velocity distribution of dark matter particles in the Solar neighborhood, and provide astronomical input parameters for the dark matter detection experiments.