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

随着时间的推移，星系性质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料。因此，了解星系冷气体成分的特性将告诉我们恒星形成过程是如何随时间变化的，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，提议者将(1)测量分子气体是如何被耗尽的，以测试星系中的恒星形成是如何受到影响的；(2)绘制这些气体在星系中的位置，以确定这些位置是否/如何影响恒星的形成；(3)测量气体如何流入和流出星系，以确定这如何影响星系随时间的结构变化。特别是，本研究可以回答的一些问题包括：什么因素影响分子气体向恒星的转化？分子气体的结构是怎样的？星系是如何成长和衰老的？这一提议将提供对星系形成过程的洞察，以及我们对这些天体的理解。本方案计划结合125个邻近星系样本的一氧化碳分子气体、电离气体和恒星群的空间分辨光谱。测量空间分辨的分子气体耗尽时间尺度作为各种星系特性的函数，使用光谱线诊断来探测弥漫的分子气体，并限制这些星系的气体进出速率，有可能大大增加我们对正常星系中恒星形成的理解。通过一系列红移对星系的观测使我们能够见证星系人口的增长和老龄化。人们早就认识到，这些过程是由恒星形成的兴衰驱动的，而恒星形成的兴衰最终与冷气体的供应有关。然而，要进一步了解星系中恒星形成的规律，除了分子气体质量和恒星形成速率之外，还需要额外的观测约束。通过利用迄今为止最大，最均匀的星系干涉CO调查（星系演化外数据库，或EDGE）和主要的正在进行的光学积分场单元（IFU）调查之一（CALIFA）的独特组合，项目团队将通过统一的，高质量的气体质量和恒星形成率测量来面对恒星形成和星系演化模型，并辅以大量的额外数据，包括恒星形成历史。恒星质量，核活动，金属丰度以及气体和恒星的运动学。这些研究将在空间分辨的基础上进行，在一个明确定义的样本上，这是附近宇宙的代表，因此将为JWST和ALMA在所有红移中进行的恒星形成和质量聚集的未来研究提供信息。

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.