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

天体物理学中一个长期存在的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，并深入了解我们银河系的起源是必要的。了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。由于恒星形成发生在星系内的巨分子云（GMCs）中，天体物理学家研究了巨分子云的形成和演化。凭借前所未有的高质量和高分辨率数据，本研究将探索星系盘中gmc的演化和随后的恒星形成，并将批判性和定量地重新考虑星系中气体演化的标准图像，特别是由恒星反馈驱动的图像。这项研究首次对大量螺旋星系中的GMC种群进行了普查。这个项目也将作为阿塔卡马大型毫米波/亚毫米波阵列（ALMA）（一个由国家科学基金会部分资助的新的国际设施）研究的原型，它将解决附近星系中gmc的内部结构，并定期产生非常遥远星系中分子气体和恒星形成的图像。在这个项目中，研究人员将使用他们用毫米波天文学联合研究阵列（CARMA）和Nobeyama射电天文台45米望远镜（NRO45）对附近星系进行的新CO调查的观测结果，该调查已接近完成。研究人员将向天文学界发布来自CARMA和NRO45附近星系的CO数据，他们还将发布为调查开发的干涉仪和单碟数据组合的软件。调查小组还计划开展教育和推广活动，包括为实践天文学实验课程建造一个无线电干涉仪，并向其他学校传播课程材料。由于干涉测量的概念很难掌握，因此开发这样一个动手实验课程对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.