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: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=763261
• 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.

以银河系来衡量恒星的位置和速度的天文学调查使我们能够了解星系的动力学及其暗物质光环的结构。我的研究小组结合了理论，模拟和数据分析来探索和探索这些调查。从2012年开始，我们的重点一直放在以下假设上：银河系的恒星磁盘表现出垂直波动的运动，即与中平面正常的运动。这项工作的推动力是我和我的合作者在附近恒星的中平面和垂直散装运动方面发现了不对称数。不久之后，其他研究人员使用不同的调查发现了类似的功能。此外，在银河系的磁盘中发现了涟漪或波纹。一种可能性是这些特征是由经过的卫星星系的重力场引起的。我的研究计划的目的是通过理论分析和仿真来搜索磁盘磁盘的新证据，并对垂直波的理解发展。此外，我的小组将探讨磁盘序列化对关键项目的含义，例如确定银河重力潜力和太阳能邻域中的暗物质数量。简而言之，这项努力是我们称之为银河系学的努力，旨在通过研究磁盘中的波浪动作来了解银河系及其环境的结构。上述发现是通过调查进行的，其中包括数十万星的星体测量。银河动力学领域现在集中在盖亚（Gaia）上，盖亚（Gaia）是一个欧洲空间观测站，该天文台将测量超过十亿颗恒星的6D相空间坐标，从而增加恒星数量，并通过相位空间测量的3-4个数量级来增加相位空间测量。盖亚（Gaia）的第二个数据发布已经为7m恒星提供了6D测量，从而产生了有趣的结果，例如太阳附近的好奇相空间螺旋。诸如此类的相空间结构为银河电位提供了潜在的强大探针。我的研究的一项作用是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。这些方法包括内核密度估计和山脊从计算机视野领域找到算法。我的研究计划还使用星系的N体模拟来检验我们的假设。 “观察”模拟快照是为了生成可以将其与实际数据进行比较的模拟数据目录。模拟还提供了一个机会来测试我们对银河系动态的理解。研究生和本科HQP将参与我的研究计划的各个方面，并将在理论天体物理学，计算方法和数据科学方面获得宝贵的培训。