Measuring Robust Pattern Speeds in a Large Sample of Spiral Galaxies

与螺旋密度波相关的最难以捉摸的测量之一是图案旋转的角频率。由于星系演化的许多性质可能取决于恒星和气体遇到密度波的频率，因此确定模式速度是至关重要的。研究人员已经证明，不久前发展起来的Tremaine-Weinberg方法现在可以成功地应用于测量以分子为主导的星际介质(ISM)的星系的模式速度，使用一氧化碳(CO)的观测。该项目将利用来自调查的档案数据，将这项工作扩展到更大的样本，并将调查是否可以使用中性氢(HI)测量来分析以中性氢为主的星系，这也是从已公布的调查中得出的。这项研究将探索将CO和HI数据结合起来研究ISM不受这两个阶段控制的星系是否可行。如果有的话，将使用所研究星系的形态和运动学数据来研究密度波理论关于共振和扩展晕效应的预测。对于条形螺旋，这项工作还将测试条形图案和螺旋图案之间的建议联系。这项研究将至少涉及一个博士论文项目，并在经认可的少数民族机构(西班牙裔服务机构)创造一个新的研究机会。结果将通过首席调查员继续在当地进行的公共宣传工作，广泛传播到社区和其他地方。

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.