Beyond the Beam: Revealing Star Formation in Galaxies through Simulations and Observations

恒星是在星系中密集的分子气体云中形成的，但是这些气体云和其中的恒星是如何形成的仍然没有被完全理解。银河系的力量可能在某种程度上发挥作用，但银河系环境的确切作用仍有待确定。利用诸如ALMA， SOFIA，即将到来的SKA及其前身等革命性设备的观测调查，现在能够第一次观察到分子云的形成，这些分子云是恒星的诞生地，从原子HI到其他星系中密集的恒星形成核心。然而，即使是最好的观测也受到分辨率、灵敏度、投影效果和光学深度问题的限制。在这个项目中，我们将寻求在模拟和观测之间进行“转换”，以了解决定分子云和恒星在不同星系环境中如何形成的关键物理参数。为此，我们将利用后处理辐射传输技术，在尖端的高分辨率星系模拟中对富含气体的区域进行综合观测。独特的是，这些模拟解决了单个分子云的亚结构，同时仍然在kpc尺度上捕获星系力。我们的合成观测将集中在创建1)21厘米线上的HI图，用于与THOR对银河系的调查、MEERKAT的观测和SKA的预测进行比较；2)CII发射图，用于与我们团队成员的SOFIA调查进行比较；3)CO分子线发射图，用于与ALMA观测进行比较。然后将这些数据与观测数据集进行比较，以确定哪些参数最能再现观测结果。这个项目将使未来的学生获得理论和观测数据的经验。

Stars form in dense clouds of molecular gas in galaxies, but how these clouds and the stars within them are formed is still not fully understood. Galactic forces are likely to play a role at some scale but the precise role of galactic environment still has to be determined. Observational surveys using revolutionary facilities such as ALMA, SOFIA, the upcoming SKA and its precursors are now able to observe the formation of the molecular clouds that are the birthplaces of stars all the way from atomic HI to dense star forming cores in other galactic systems for the first time. However, even the best observations are limited by resolution, sensitivity, projection effects and issues of optical depth. In this project we will seek to "translate" between simulations and observations to learn the key physical parameters that determine how molecular clouds and stars form in different galactic environments. We will do this by creating synthetic observations of gas-rich regions in cutting-edge high-resolution galaxy simulations using post-process radiative transfer. Uniquely these simulations resolve individual molecular clouds sub-structure while still capturing galactic forces on kpc scales. Our synthetic observations will focus on creating 1) HI maps in the 21 cm line for comparison to the THOR survey of the Milky Way, observations from MEERKAT, and predictions for the SKA, 2) CII emission maps for comparison to a SOFIA survey our team is a member of and 3) CO molecular line emission for comparison to ALMA observations. These will then be compared to the observational data sets to determine what parameters best reproduce the observations. This project will allow the prospective student to gain experience with both theoretical and observational data.