Collaborative Research: Chemistry in the Centers of Nearby Galaxies

转弯分子云是宇宙演化的主要原因，包括恒星诞生、星系合并和活跃星系核的形成。不幸的是，这种气体主要是分子氢，不容易辐射，因此观测必须依赖于更容易检测到的示踪剂分子，其中最常见的是一氧化碳(CO)。然而，在能量最高的区域，云化学的变化意味着其他分子可能是更好的示踪剂。附近恒星爆发星系的单盘光谱表明，星系之间的全球化学差异可能是显著的，这让人质疑使用CO，或者实际上，任何其他单一分子作为分子云和气体质量的示踪剂。这个项目将专注于最近的螺旋星系中心的化学性质，在那里巨型分子云可以在线条图像中被分解，研究至少七个分子并寻找关联，试图找到云化学的简单表征。这项关于星系化学成像的工作是此类工作的第一次。除了揭示这些星系的天体物理环境外，这项研究还可能对单个化学反应施加限制，识别气相和气粒化学，并致力于利用未来的毫米阵列仪器研究更远更远的星系。

AST-0506469TurnerMolecular clouds are responsible for much of the evolution in the Universe, including starbirth, galaxy mergers, and the fueling of active galactic nuclei. Unfortunately, this gas is mostly molecular hydrogen, which does not radiate easily, and so observations must rely on tracer molecules that are more easily detected, the commonest of which is carbon monoxide (CO). However, in the most energetic regions, changes in cloud chemistry mean that other molecules may be better tracers. Single-dish spectra of nearby starburst galaxies show that global chemical differences among galaxies can be significant, which calls into question the use of CO, or, indeed, any other single molecule as a tracer of molecular clouds and gas mass. This project will focus on the chemical properties of the centers of the closest spiral galaxies, where giant molecular clouds can be resolved in line images, studying at least seven molecules and looking for correlations, trying to find simple characterizations of the cloud chemistry.This work on the chemical imaging of galaxies is the first of its kind. In addition to revealing the astrophysical environments in these galaxies, this research may place constraints on individual chemical reactions, identifying gas-phase and gas-grain chemistry, and working towards the study of many, much more distant, galaxies with future millimeter array instruments.