Integrated Models of Magnetic Fields and Gas Kinematics in Molecular Clouds

分子云中磁场和气体运动学的集成模型

• 批准号: RGPIN-2017-05930
• 负责人: Fiege, Jason
• 金额: $ 1.53万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=711891
• 关键词: Integrated; Models; Magnetic; Fields; Gas

Molecular clouds are magnetized, turbulent, self-gravitating structures, and the seat of star formation in our Galaxy. Star formation occurs on small scales (~0.1 pc), in dense cores, where gravity overcomes turbulence and outward magnetic forces. Magneto-centrifugal forces drive a pair of jets, which sweep up surrounding gas into a pair of bipolar molecular outflows. Self-gravity, outflows, and magnetic fields are strongly coupled in star formation. An integrated data-driven modelling approach, which takes into account these components simultaneously, will provide a clear picture of star forming regions. My HQP and I have developed a software package called PolCat, which uses a novel method to search an enormous space of potential density/magnetic field configurations, to automatically find those that best fit sub-millimetre polarization and intensity maps. Our models are often degenerate, but we easily rule out field geometries that cannot explain the data, and find geometries that work. PolCat models are triaxial and do not assume detailed equilibrium. However, we will use the tensor virial theorem to reject core models that are far from equilibrium along any principal axis, thus providing tighter model constraints. We will also develop a complementary method, based on the self-consistent field method of MHD, to rapidly calculate axisymmetric equilibrium models of rotating, magnetized, self-gravitating cores. The most important extension to PolCat will be a new component to model molecular outflows and their CO (carbon monoxide) line emission. My HPQ and I will develop integrated three-dimensional modelling methods, built upon techniques developed by my group, to generate and constrain models of magnetized star-forming cores and their outflows using observational data. We will explore the relationship between a core's magnetic field and the structure and orientation of outflows by applying our models to data from the BISTRO survey, which uses the new POL-2 polarimeter at the James Clerk Maxwell Telescope. A related line of inquiry will investigate the recently discovered phenomenon of molecular tornadoes, which are pressure-bound, rotating, helically-wound molecular filaments near the Galactic Centre. It is believed that their striking helical structure arises from the magnetohydrodynamic instability of a twisted magnetic tube, which is wrapped up by a torsional Alfven wave propagating along the filament. My HQP and I will develop a comprehensive, observationally constrained theory of molecular tornadoes and their stability, which will explain their unusual morphology. We will predict submillimetre polarization maps due to these objects, for comparison with future observations. The overarching goal of this research program is to develop new models and computational tools leading to an improved understanding of magnetic fields in molecular clouds and star formation.

分子云是磁化的、湍流的、自引力的结构，是我们银河系中星星形成的所在地。 星星的形成发生在小尺度（~0.1 pc），在致密的核心，重力克服湍流和向外的磁力。 磁离心力驱动一对射流，将周围的气体扫入一对双极分子外流。 在星星的形成过程中，自引力、外流和磁场是强耦合的。 一个综合的数据驱动的建模方法，同时考虑到这些组成部分，将提供一个清晰的星星形成区域的图片。 我和我的HQP开发了一个名为PolCat的软件包，它使用一种新颖的方法来搜索潜在密度/磁场配置的巨大空间，以自动找到最适合亚毫米偏振和强度图的那些。 我们的模型通常是退化的，但我们很容易排除无法解释数据的场几何，并找到有效的几何。 PolCat模型是三轴的，不假设详细的平衡。 然而，我们将使用张量维里定理拒绝远离平衡的核心模型，沿着任何主轴，从而提供更严格的模型约束。 我们也将发展一种互补的方法，基于MHD的自洽场方法，来快速计算旋转、磁化、自引力磁芯的轴对称平衡模型。 PolCat最重要的扩展将是一个新的组件，用于模拟分子流出及其CO（一氧化碳）线排放。我的HPQ和我将开发集成的三维建模方法，建立在我的团队开发的技术基础上，使用观测数据生成和约束磁化恒星形成核心及其流出物的模型。 我们将探讨核心的磁场和结构和方向的外流应用我们的模型从BISTRO调查，它使用新的POL-2偏振计在詹姆斯克拉克麦克斯韦望远镜的数据之间的关系。 一个相关的调查将调查最近发现的分子龙卷风现象，这是压力约束，旋转，螺旋缠绕的分子细丝附近的银河系中心。 据信，它们引人注目的螺旋结构产生于扭曲的磁管的磁流体动力学不稳定性，该磁管被沿丝沿着传播的扭转阿尔芬波包裹。 我和我的HQP将开发一个全面的，观测约束理论的分子龙卷风和他们的稳定性，这将解释他们不寻常的形态。 我们将预测由于这些物体的亚毫米极化图，与未来的观测进行比较。 这项研究计划的首要目标是开发新的模型和计算工具，从而提高对分子云和星星形成中磁场的理解。