Evolving Gas Chemistry and Star Formation in Local Galaxies

在这个项目中，通过分析附近星系样本中巨大分子云复合体的分子线发射来研究化学与恒星形成之间的关系。这是利用毫米波天文学研究联合阵列（CARMA）和射电天文学研究所（Institut de Radio Astronomy milimastrique）在厘米和毫米波长进行的高空间分辨率天体化学观测完成的。(族长)干涉仪。主要目标是表现出不同结构和恒星形成特性的局部星系的内部凸起。天体化学和形态学的诊断有助于揭示星系演化的调控机制。这项工作寻找由恒星形成和大规模动力学引入星际介质分子组成的化学变化，反之亦然，它确定了这些过程的化学示踪剂。有些气体被认为是特定过程的示踪剂，但可能很难观察到。其他更容易观察到的分子可以作为难以观察到的分子的替代品，但需要识别更多的分子。这些观测结果提供了分子线列表，为即将到来的阿塔卡马大型毫米波阵列（ALMA）和扩展甚大阵列（EVLA）的观测提供了探路者。具体来说，化学是通过分析喷射颗粒的大尺度分布变化来解构冲击的能量学和亚结构。第二个应用是研究Schmidt-Kennicutt恒星形成定律的斜率及其对给定化学示踪剂的灵敏度。第三项研究分析了在光解作用重要的恒星形成区域中分子气体状态的变化。这项工作更广泛的影响在于它对天体化学的强烈关注。随着ALMA和EVLA观测越来越近，各种大规模环境的重要分子示踪剂列表对社区来说是一笔有用的资产。其他领域，如星系动力学和恒星演化也受益于激波结构和恒星反馈示踪剂的识别。参与这个项目的研究生将被训练成为一个活跃的ALMA和EVLA用户。作为这个项目的一部分，我们为高中和大学设计了“化学的力量”系列海报，它描述了化学在大范围内的作用，从这项工作中得到的化学显然跨越了最大的维度。希望这有助于吸引学生从事科学事业。

In this project, the relationship between chemistry and star formation is studied by analyzing molecular line emissions from complexes of giant molecular clouds in a sample of nearby galaxies. This is done with high spatial resolution astrochemical observations at cm and mm wavelengths using the Combined Array for Research in Millimeter-Wave Astronomy (CARMA) and the Institut de Radio Astronomie Millimétrique? (IRAM) interferometers. Main targets are the inner bulges of local galaxies that show different structural and star formation properties. The diagnostics from astrochemistry and morphological studies can shed light on the regulating mechanisms of galaxy evolution. This work looks for the chemical changes that are introduced in the molecular composition of the interstellar medium by star formation and large scale dynamics, or vice versa, it identifies chemical tracers for these processes. Some gas species are known as tracers of particular processes, but may be difficult to observe. Other, easier observable molecules can serve as proxies for the molecules that are difficult to observe, but more of these need to be identified. The observations provide molecular line lists that serve as pathfinder for the coming observations with the Atacama Large Millimeter Array (ALMA) and Expanded Very Large Array (EVLA). Specifically, the chemistry is used to deconstruct the energetics and substructure of shocks by analyzing the changes in large-scale distribution of ejected grain species. A second application is to investigate the slopes of Schmidt-Kennicutt star formation law and their sensitivities for a given chemical tracer. A third study analyzes changes in the state of molecular gas in star-forming regions where photo-dissociation is important.The broader impact of this work is its strong astrochemical focus. The list of important molecular tracers for the various large-scale environments is a useful asset for the community as ALMA and EVLA observations are coming closer. Other fields such as galactic dynamics and stellar evolution also benefit from the identification of tracers of shock structure and stellar feedback. The graduate student who participates in this project will be well trained to be an active ALMA and EVLA user. As part of this project, a "powers of chemistry" poster series for high schools and colleges is developed which describes the role of chemistry over a wide range of scales and the chemistry from this work clearly spans the largest dimensions. It is hoped that this helps to attract students to pursue scientific careers.