Constraining the structure and history of the Milky Way disk using Gaia

由于离我们很近，银河系提供了一个独特的实验室，可以细致地研究一个巨大的盘状星系。我们目前正生活在银河考古学的黄金时代，能够利用多个恒星群的运动学、化学丰度和精确的年龄估计来研究银河系的形成历史和结构。随着最近欧空局盖亚任务的第二和早期第三次数据发布（DR2和EDR3），这一领域发生了范式转变。在恒星多维化学丰度和运动学相空间中进行了前所未有的详细诊断。这引发了关于盘的动态状态、旋臂和中央棒的性质以及合并卫星（例如人马座矮星系）的影响的争议。该提案的目标是通过使用最先进的数值模型来解释盖亚DR3数据，结合现有的和即将到来的地面光谱数据（APOGEE, SDSS-V， GALAH和WEAVE， 4MOST），以及来自CoRoT，开普勒和K2任务的星震数据，来限制关键的结构属性和银河系盘的形成。化学丰度和精确年龄可以与恒星的诞生位置有关，这对于在相互竞争的模型中进行区分是极其重要的。我们的模型将主要基于AIP即将进行的高分辨率HESTIA模拟，该模拟使用最先进的AREPO/Auriga星系形成代码在本星系群环境中模拟银河系。在模型和数据的比较中，我们将考虑选择效应和观测误差。我们将通过考虑以下相互关联的问题，为不同的银河系演化场景提供测试：(1)根据最近来自星系和内部因子（条形和旋臂）的扰动，理解盖亚DR2数据中丰富的相空间结构（速度-位置空间中的脊状、拱状和蜗牛壳螺旋）；(2)通过研究单年龄恒星群的盘厚和速度色散径向分布，以及轨道性质随年龄的变化，恢复银河系盘的扩展合并历史；(3)考虑宇宙学背景下真实的时间演化模型，结合动力学、化学和年龄信息，约束银河系的条形和螺旋结构参数。

Due to our proximity, the Milky Way provides a unique laboratory to study a massive disk galaxy in exquisite detail. We are currently living in the golden age of Galactic Archaeology, being able to investigate the formation history and structure of our Galaxy using multiple stellar populations with kinematics, chemical abundance, and age estimates with excellent precision. A paradigm shift has occurred in this field with the recent second and early third data releases (DR2 and EDR3) from ESA’s Gaia mission. Detailed diagnostics as never before have already been performed in the stellar multi-dimensional chemical abundance and kinematics phase space. This has fueled controversies about the dynamical state of the disk, the nature of spiral arms and central bar, and the effect of merging satellites (e.g., the Sagittarius dwarf galaxy). The goal of the proposal is to constrain key structural properties and the formation of the Milky Way disk, by using state-of-the-art numerical models for the interpretation of the Gaia DR3 data, combined with available and upcoming ground-based spectroscopic data (APOGEE, SDSS-V, GALAH and WEAVE, 4MOST), as well as the asteroseismic data from CoRoT, Kepler, and K2 missions. Chemical abundances and precise ages can be related to the birth positions of stars, which is extremely important for discriminating among competing models. Our models will be mostly based on the upcoming high-resolution HESTIA simulations at the AIP, which simulate the Milky Way in the Local Group environment using the state-of-the-art AREPO/Auriga galaxy formation code. In the comparison between models and data we will account for both selection effects and observational errors. We will provide tests for different Milky Way evolutionary scenarios by considering the following interconnected problems: (1) Understand the rich phase-space structure found in the Gaia DR2 data (ridges, arches, and snail-shell spiral in velocity-position space) in terms of recent perturbations from infalling galaxies and from internal agents (bar and spiral arms), (2) Recover the extended merger history of the Milky Way disk by studying disk thickness and velocity dispersion radial profiles for mono-age groups of stars, as well as changes in orbital properties with age, and (3) Constrain the Milky Way bar and spiral structure parameters by considering realistic time-evolving models in the cosmological context and combining dynamics, chemistry and age information.