POWRE: The Evolution of Elliptical Galaxies: New Clues from Neutral Gas

近些年来，椭圆星系并不像人们曾经认为的那样是死亡的、无气体的星系，这一点已经变得清晰起来。它们中的许多含有中性气体，这增加了它们可能正在形成恒星的有趣可能性。对椭圆星系演化的完整理解依赖于知道这种中性气体的起源和命运，以及椭圆星系中的恒星形成速率。通过观测九个椭圆星系的一氧化碳(CO)和氢(HI)发射线，将使用伯克利、伊利诺伊州和马里兰州(BIMA)和欧文斯山谷射电天文台(OVRO)毫米波长射电望远镜干涉仪和甚大阵列(VLA)射电望远镜拍摄高分辨率图像。对中性气体分布和运动学数据的分析将为其起源和命运提供重要线索。例如，对数据的分析将显示气体是否是在猛烈的合并中获得的，无论是正在形成恒星、正在为活跃的星系核提供食物，还是正在被某些其他过程摧毁。关于气体分布和运动学的知识也将有助于解释椭圆星系中无线电-FIR关联的起源，并将揭示星系环境对其中性气体的影响。这些问题的答案尚不清楚，因为很少有椭圆星系有关于其分子和原子气体分布的良好数据。这个项目的结果将使拥有良好的CO和HI发射线图的椭圆星系的数量增加一倍以上。样本星系具有广泛的性质(包括环境、形态、光度等)。和核连续谱源的强度)，这将有助于解开影响椭圆星系的许多过程。该项目的结果将是一个独特的信息合成，这将有助于给出一个更好的椭圆星系及其星际介质的全球图像。该项目关于单个椭圆星系恒星形成率的结果将与Cotton&Amp；London(1998)的统计工作相结合，给出椭圆星系中恒星形成的第一张定量图片。该项目的结果还将用于完善椭圆星系演化的理论模型。最后，通过展示椭圆星系今天的演化，该项目将有助于确定高红移和低红移星系之间的联系。该项目由天文学司和数学和物理科学局多学科活动办公室资助。*

AST-007409YoungIn recent years it has become clear that elliptical galaxies are not dead, gas-free galaxies as they were once thought to be. Many of them contain neutral gas, which raises the interesting possibility that they may be forming stars. A complete understanding of elliptical galaxy evolution depends on knowing the origin and the fate of this neutral gas and the star formation rate in elliptical galaxies. High resolution images made from observations of the carbon monoxide (CO) and hydrogen (HI) emission lines from nine elliptical galaxies will be made with the Berkeley, Illinois, and Maryland (BIMA) and Owens Valley Radio Observatory (OVRO) millimeter wavelength radio telescope interferometers and with the Very Large Array (VLA) radio telescope. The analysis of the data on the neutral gas distribution and kinematics will give vital clues to its origin and its fate. For example, the analysis of the data will show whether the gas was acquired in a violent merger, whether the gas is forming stars, is feeding an active galactic nucleus, or is being destroyed by some other process. The knowledge about the gas distribution and kinematics will also help explain the origin of the radio-FIR correlation in elliptical galaxies and will reveal the effects of a galaxy's environment on its neutral gas.The answers to these questions are not known because there are very few elliptical galaxies with good data on the distribution of their molecular and atomic gas. The results from this project will more than double the number of elliptical galaxies with good CO and HI emission line maps. The sample galaxies have a wide range of properties (including environment, morphology, luminosity. and strength of nuclear continuum source), that will help to disentangle the many processes affecting elliptical galaxies. The result from the project will be a unique synthesis of information that will help to give a better global picture of elliptical galaxies and their interstellar media. The project's results on the star formation rates in individual elliptical galaxies will be combined with the statistical work of Cotton & London (1998) to give the first quantitative picture of star formation in elliptical galaxies. The results of this project will also he used to refine the theoretical models of elliptical galaxy evolution. Finally, by showing how elliptical galaxies are evolving today, the project will help to draw the connections between high redshift and low redshift galaxies.This project is funded by the Division of Astronomical Sciences and the Office of Multidisciplinary Activities in the Mathematical and Physical Sciences Directorate.***