New CO(1-0) Survey of Nearby Galaxies: Evolution of Molecular Gas and Star Formation in Galactic Disks

天体物理学中的一个长期问题是了解星系在其一生中是如何形成和发展的。这样的理解对于揭示我们的宇宙是如何进化的以及洞察我们银河系的起源是必要的。理解星系形成和演化的一个重要方面是发展恒星形成的详细理论。由于恒星是在星系内的巨型分子云(GMC)中形成的，天体物理学家研究了GMC的形成和演化。这项研究将利用前所未有的高质量和高分辨率数据，探索星系盘中GMC的演化和随后的恒星形成，并将批判性地和定量地重新考虑星系中气体演化的标准图景，特别是由恒星反馈驱动的演化图景。这项研究首次能够对大量螺旋星系中的GMC种群进行普查。该项目还将作为阿塔卡马大毫米/亚毫米阵列(ALMA)研究的原型，ALMA是一个新的国际设施，部分由国家科学基金会资助，它将解析附近星系中GMC的内部结构，并定期产生分子气体和遥远星系中恒星形成的图像。在这个项目中，研究人员将使用他们新的对附近星系的CO调查的观测结果，以及联合毫米波天文研究阵列(CARMA)和Nobeama射电天文台45米望远镜(NRO45)，这是一项即将完成的调查。研究人员将向天文界发布CARMA和NRO45附近星系的CO数据，他们还将发布干涉仪和单盘数据组合的软件。调查小组还计划开展教育和推广活动，包括为实际操作的天文实验室课程建造无线电干涉仪，并将课程材料分发给其他学校。由于干涉测量的概念很难掌握，因此开发这样一门动手实验室课程对ALMA时代下一代射电天文学家的教育至关重要。

A longstanding problem in astrophysics is to understand how galaxies form and develop throughout their lifetimes. Such understanding is necessary to uncover how our Universe evolved and to gain insight into the origin of our own Milky Way Galaxy. One important aspect of understanding galaxy formation and evolution is to develop detailed theories of star formation. As star formation occurs in giant molecular clouds (GMCs) within galaxies, astrophysicists study the formation and evolution of GMCs. With unprecedented high quality and high resolution data, this study will explore the evolution of GMCs and consequent star formation in galactic disks, and it will critically and quantitatively reconsider the standard picture of gas evolution in galaxies, specifically the one driven by stellar feedback. The study enables for the first time a census of GMC populations in substantial spiral galaxies.This project will also serve as a prototype for research with the Atacama Large Millimeter/submillimeter Array (ALMA) (a new international facility funded in part by the National Science Foundation), which will resolve the internal structure of GMCs in nearby galaxies and routinely produce images of molecular gas and star formation in very distant galaxies. For this project the investigators will use observations from their new CO survey of nearby galaxies with the Combined Array for Research in Millimeter-wave Astronomy (CARMA) and the Nobeyama Radio Observatory 45m telescope (NRO45), a survey that is nearly complete. The investigators will release to the astronomical community the CO data of nearby galaxies from CARMA and NRO45, and they will also release the software for the combination of interferometer and single-dish data developed for the survey.The investigating team also plans educational and outreach activities that involve building a radio interferometer for a hands-on astronomical laboratory course and disseminating the course materials to other schools. Because the concept of interferometry is challenging to master, developing such a hands-on laboratory course is crucial to the education of the next generation of radio astronomers for the ALMA era.