Measuring Robust Pattern Speeds in a Large Sample of Spiral Galaxies

与螺旋密度波有关的最难以捉摸的测量之一是该模式旋转的角频率。由于星系演化的许多特性可能取决于恒星和气体遇到密度波的频率，因此确定模式速度至关重要。研究人员已经证明，不久前开发的Tremaine-Weinberg方法现在可以成功地应用于用分子主导的星际介质（ISM）测量星系中的模式速度，使用一氧化碳（CO）的观测。这个项目将把这项工作扩展到一个更大的样本，使用来自调查的档案数据，并将调查是否可以使用中性氢（HI）测量来分析具有中性氢主导的ISM的星系，也来自已发表的调查。本研究将探索将CO和HI数据结合起来研究ISM不以任何一相为主的星系是否可行。在可能的情况下，所研究星系的形态学和运动学数据将用于研究有关共振和扩展晕效应的密度波理论的预测。对于条形螺旋，这项工作还将测试条形图案和螺旋形图案之间的联系。该研究将涉及至少一个博士论文项目，并在认可的少数民族机构（西班牙裔服务）创造一个新的研究机会。通过首席研究员持续的当地公共宣传工作，研究结果将广泛传播到社区内外。

AST-0306958RandOne of the most elusive measurements associated with spiral density waves is that of the angular frequency with which the pattern rotates. Since many properties of galaxy evolution may depend on how frequently stars and gas encounter density waves, determining pattern speeds is of fundamental importance. The researcher has already shown that the Tremaine-Weinberg method developed some while ago can now be successfully applied to measuring pattern speeds in galaxies with a molecular-dominated interstellar medium (ISM), using observations of carbon monoxide (CO). This project will extend that work to a much larger sample, using archival data from surveys, and will investigate whether galaxies with a neutral-hydrogen-dominated ISM can be analyzed using neutral hydrogen (HI) measurements, also from published surveys. This research will explore whether it is feasible to combine both CO and HI data to study galaxies whose ISM is not dominated by either phase.Where available, morphological and kinematic data for the studied galaxies will be used to investigate the predictions of density-wave theory concerning resonances and the effect of extended haloes. For barred spirals, this work will also test suggested connections between the bar pattern and the spiral pattern.The research will involve at least one doctoral thesis project, and create a new research opportunity at an accredited Minority Institution (Hispanic Serving). The results will be spread widely to the community and beyond, through the principal investigator's continuing local public outreach work.