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型分子云复合体的分子线发射，研究了化学和恒星形成之间的关系。这是通过使用毫米波天文研究组合阵列(CARMA)和射电天文研究所Millimétrique？进行厘米和毫米波长的高空间分辨率天文观测完成的。(IRAM)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。来自天体化学和形态研究的诊断可以揭示星系演化的调节机制。这项工作寻找恒星形成和大尺度动力学在星际介质的分子组成中引入的化学变化，或者反之亦然，它确定了这些过程的化学示踪剂。一些气体物种被认为是特定过程的示踪物，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，但其中更多的分子需要被识别。这些观测提供了分子线表，作为阿塔卡马大毫米阵列(ALMA)和扩展甚大阵列(EVLA)下一次观测的探路者。具体地说，通过分析抛射颗粒大尺度分布的变化，利用化学来解构激波的能量和亚结构。第二个应用是研究施密特-肯尼库特恒星形成定律的斜率及其对给定化学示踪剂的敏感性。第三项研究分析了恒星形成区域中分子气体状态的变化，在那里光解是重要的。这项工作的更广泛影响是它强烈的天体化学焦点。随着ALMA和EVLA的观测越来越近，各种大规模环境的重要分子示踪剂清单对社区来说是一项有用的资产。其他领域，如星系动力学和恒星演化，也得益于激波结构和恒星反馈示踪物的识别。参与该项目的研究生将接受良好的培训，成为一名活跃的ALMA和EVLA用户。作为该项目的一部分，为高中和大学制作了一系列“化学的力量”海报，它描述了化学在广泛范围内的作用，这项工作中的化学显然跨越了最大的维度。希望这有助于吸引学生追求科学职业。

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.