Collaborative Research: Changes in Molecular Gas and Galaxy Properties Over Time in the Era of Integral Field Unit Surveys

星系性质随时间的变化是由其冷气体的数量驱动的，冷气体是恒星形成的原材料。因此，了解星系冷气体成分的性质将告诉我们恒星形成过程如何随着时间的推移而变化，以及这是如何影响星系的。利用最近完成的对附近星系样本中一氧化碳气体的调查，提出者将(1)测量分子气体是如何用完的，以测试星系中的恒星形成是如何受到影响的；(2)绘制这种气体在星系中的位置图，以确定这些位置是否/如何影响恒星的形成；以及(3)测量气体如何流入和流出星系，以确定这如何影响星系的结构随时间的变化。特别是，这项研究可以回答的一些问题包括：哪些因素影响分子气体转化为恒星？分子气体是如何构成的？星系是如何生长和老化的？这项提议将提供对星系形成过程的洞察和我们对这些天体的理解。第二部分，这项提议计划结合一氧化碳分子气体、电离气体和恒星群的空间分辨光谱，为125个附近的星系提供样本。测量空间分辨的分子气体耗尽时间尺度作为不同星系属性的函数，使用光谱线的诊断来探测漫射分子气体，并限制这些星系的气体流入和流出的速率，这将极大地增加我们对正常星系中恒星形成的理解。对不同红移范围内的星系的观测使我们能够见证星系数量的增长和老化。人们早就认识到，这些过程是由恒星形成的起伏驱动的，而恒星形成的起伏最终与冷气体的供应有关。然而，在理解星系中恒星形成规律的进一步进展中，除了分子气体质量和恒星形成速率之外，还需要额外的观测限制。通过利用迄今为止最大、最均匀的星系CO干涉测量(星系外星系演化数据库，或EDGE)和正在进行的主要光学积分场单元(IFU)测量(CALIFA)的独特组合，项目组将用统一、高质量的气体质量和恒星形成速率测量来对抗恒星形成和星系演化模型，并辅之以大量额外数据，包括恒星形成历史、恒星质量、核活动以及气体和恒星的金属丰度和运动学。这些研究将在空间分辨率的基础上对代表附近宇宙的定义明确的样本进行，从而为未来JWST和ALMA进行的所有红移时恒星形成和质量组装的研究提供信息。

Part 1Changes of a galaxy's properties over time are driven by the quantity of its cold gas, the raw material from which stars form. Thus, understanding the properties of a galaxy's cold gas component will tell us both how the star formation process changes over time and how this affects galaxies. Using a recently completed survey of carbon monoxide gas in a sample of nearby galaxies, the proposers will (1) measure how the molecular gas is used up, in order to test how star formation in the galaxies is affected; (2) map the locations of this gas in the galaxies to determine if/how these locations affect star formation; and (3) measure how the gas is flowing into and out of the galaxies to determine how this affects structural changes in the galaxies over time. In particular, some questions that can be answered from this research include: What factors affect the conversion of molecular gas into stars? How is molecular gas structured? How do galaxies grow and age? This proposal will provide insight into the process of galaxy formation and our understanding of these objects.Part 2This proposal plans to combine spatially resolved spectroscopy of carbon monoxide molecular gas, ionized gas and stellar populations for a sample of 125 nearby galaxies. Measuring spatially-resolved molecular gas depletion time scales as a function of various galaxy properties, using diagnostics of spectral lines to probe diffuse molecular gas, and constraining the rates of gas in- and outflow for these galaxies has the potential to add greatly to our understanding of star formation in normal galaxies.Observations of galaxies across a range of redshifts allow us to witness the growth and aging of the galaxy population. It has long been recognized that these processes are driven by the rise and fall of star formation, which is ultimately linked to the supply of cold gas. Further progress in understanding the regulation of star formation in galaxies, however, requires additional observational constraints beyond the molecular gas mass and star formation rate. By exploiting a unique combination of the largest, most homogeneous interferometric CO survey of galaxies to date (the Extragalactic Database for Galaxy Evolution, or EDGE) and one of the principal ongoing optical integral field unit (IFU) surveys (CALIFA), the project team will confront models of star formation and galaxy evolution with uniform, high quality measurements of gas masses and star formation rates, supplemented by a vast array of additional data, including star formation history, stellar mass, nuclear activity, and the metallicity and kinematics of the gas and stars. These studies will be conducted on a spatially resolved basis across a well-defined sample that is representative of the nearby Universe, and will thus inform future studies of star formation and mass assembly at all redshifts undertaken by JWST and ALMA.