Origin, Evolution, and Implications of Wavelike Motions in the Stellar Disk of the Milky Way

银河系恒星盘中波状运动的起源、演化和影响

• 批准号: RGPIN-2019-04691
• 负责人: Widrow, Lawrence
• 金额: $ 2.48万
• 依托单位: Queen's University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=737791
• 关键词: Origin; Evolution; Implications; Wavelike; Motions

Astronomical surveys that measure the positions and velocities of stars in the Milky Way allow us to learn about the dynamics of the Galaxy and the structure of its dark matter halo. My research group uses a combination of theory, simulations, and data analysis to explore and exploit these surveys. Beginning in 2012, our focus has been on the hypothesis that the stellar disk of the Milky Way exhibits vertical wavelike motions, that is, motions normal to its midplane. The impetus for this work was the discovery by me and my collaborators of asymmetries in stellar number counts with respect to the midplane and vertical bulk motions of nearby stars. Soon after, similar features were found by other researchers using different surveys. In addition, ripples or corrugations were discovered in the further out in the Milky Way's disk. One possibility is that these features were caused by the gravitational field of a passing satellite galaxy. The goal of my research program is to search for new evidence of a perturbed disk and develop an understanding of vertical waves through theoretical analysis and simulations. In addition, my group will explore the implications of disk disequilibrium for key projects such as the determination of the Galactic gravitational potential and the amount of dark matter in the Solar Neighbourhood. In short, this endeavour, which we have dubbed Galactoseismology, aims to learn about the structure of the Galaxy and its environment by studying wavelike motions in the disk. The discoveries described above were made with surveys that included astrometric measurements of hundreds of thousands of stars. The field of Galactic Dynamics is now focused on Gaia, a European Space Observatory that will measure 6D phase space coordinates for over one billion stars and thereby increase the number of stars with phase space measurements by a staggering 3-4 orders of magnitude. Already, Gaia's 2nd Data Release, which provides 6D measurements for 7M stars, has produced intriguing results, such as curious phase space spirals near the Sun. Phase space structures such as these provide a potentially powerful probe of the Galactic potential. One thrust of my research will be to apply data science methods to the analysis of the Gaia data in an effort to uncover other features in the distribution of stars. These methods include kernel density estimation and ridge finding algorithms from the field of computer vision. My research program also uses N-body simulations of galaxies to test our hypotheses. The simulation snapshots are "observed" to generate mock data catalogs that can be compared with actual data. Simulations also provide an opportunity to test our understanding of galactic dynamics. Graduate and undergraduate HQP will be involved in all aspects of my research program and will gain valuable training in theoretical astrophysics, computational methods, and data science.

测量银河系中恒星的位置和速度的天文调查使我们能够了解银河系的动力学及其暗物质晕的结构。我的研究小组结合理论、模拟和数据分析来进行探索和研究。从 2012 年开始，我们的重点一直放在银河系恒星盘表现出垂直波状运动的假设上，即垂直于其中平面的运动。这项工作的推动力是我的发现。不久之后，其他研究人员使用不同的调查发现了恒星数量相对于附近恒星的中平面和垂直整体运动的不对称性。此外，在更远的地方也发现了波纹或波纹。银河系圆盘的一种可能性是，这些特征是由经过的卫星星系的引力场引起的。我的研究计划的目标是寻找扰动圆盘的新证据，并通过理论分析和发展对垂直波的理解。此外，我的小组将探索盘不平衡对关键项目的影响，例如确定银河系引力势和太阳邻域中的暗物质数量。简而言之，这项我们称之为银河地震学的努力的目标是。通过研究盘中的波状运动来了解银河系的结构及其环境 上述发现是通过对数十万颗恒星进行天体测量而得出的。 Dynamics 现在的重点是盖亚 (Gaia)，这是一个欧洲空间天文台，它将测量超过 10 亿颗恒星的 6D 相空间坐标，从而将相空间测量的恒星数量增加惊人的 3-4 个数量级，这已经是盖亚的第二次数据发布。提供了 700 万颗恒星的 6D 测量结果，例如太阳附近的奇特相空间螺旋，这些为银河系潜力提供了潜在的强大探测。将数据科学方法应用于盖亚数据的分析，以揭示恒星分布的其他特征，这些方法包括计算机视觉领域的核密度估计和脊寻找算法。星系的体模拟来测试我们的假设。模拟快照被“观察”以生成可以与实际数据进行比较的模拟数据目录，模拟还提供了一个测试我们对星系动力学的理解的机会。的各个方面我的研究计划并将获得理论天体物理学、计算方法和数据科学方面的宝贵培训。