Collaborative Research: Establishing the Physical Picture for Rest-optical Emission Lines in Star-forming Galaxies from Cosmic Noon to Cosmic Dawn

天文学家的目标是测量星系在宇宙时间内的几个基本性质。其中包括新星诞生的速度、所谓重元素的比例（例如，氧）相对于氢，以及星际介质（ISM）所暴露的辐射场的性质（无论是来自大质量恒星的光还是来自超大质量黑洞的吸积）。这些关键的星系性质通常是从电离ISM产生的光谱发射线的模式推断出来的。然而，研究表明，相对于当今宇宙中观察到的情况，在宇宙时间的前几十亿年内观察到的星系中，星系光谱与该星系中普遍存在的潜在物理条件之间的转换可能存在质的不同。Shapley和Sanders将分析大约100亿年前观察到的数百个星系的数据，当时宇宙正处于恒星形成的高峰期，以建立星系光谱和物理性质之间的基本转换。他们还将为社区建立一个公开可用的软件工具，用于在大爆炸后的第一个十亿年内对星系的光谱进行建模。沙普利和桑德斯还将参与公共宣传方面的几项工作，与世界望远镜大使计划合作，就天文光谱学等主题开发跨夜空的互动图尔斯之旅。他们将把这些教学材料纳入各自校区正在进行的外展工作中。关于将静止光学发射线特性转化为物理特性，存在一些重要问题（例如，恒星形成率，气相氧丰度，电离参数）。co-PI已经从凯克MOSFIRE深演化场（MOSDEF）调查中收集了z=1.5-2.5恒星形成星系的最终样本。他们将使用这个样本来建立星系发射线和物理性质之间的转换，并建立和公开发布一个软件工具，用于对遥远星系的静止光学发射线光谱进行鲁棒建模，一直追溯到宇宙黎明（z6）。随着我们进入近红外光谱学的新时代，在太空中建立大型天文台，拟议的产品将提供持久的遗产。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Astronomers aim to measure several fundamental properties of galaxies across cosmic time. These include the rate at which new stars are being born, the proportion of so-called heavy elements (e.g., oxygen) relative to hydrogen, and the nature of the radiation field to which the interstellar medium (ISM) is exposed (be it light from massive stars or from accretion onto a supermassive black hole). These key galaxy properties are commonly inferred from the pattern of spectral emission lines produced by the ionized ISM. However, it has been shown that the translation between the spectrum of a galaxy and the underlying physical conditions prevailing in that galaxy may be qualitatively different in galaxies observed within the first few billion years of cosmic time, relative to what is observed in the universe today. Shapley and Sanders will analyze data from several hundred galaxies, observed roughly 10 billion years ago when the universe was forming stars at its peak level, to establish this essential translation between galaxy spectral and physical properties. They will also build a publicly available software tool for the community for modeling the spectra of galaxies all the way back to cosmic dawn within the first billion years after the Big Bang. Shapley and Sanders will also engage in several efforts in public outreach, partnering with the WorldWide Telescope Ambassadors Program to develop interactive tours across the night sky on topics such as astronomical spectroscopy. They will incorporate these pedagogical materials into ongoing outreach efforts at each of their respective campuses.There are important questions regarding the translation of rest-optical emission line properties to physical ones (e.g., star-formation rate, gas-phase oxygen abundance, ionization parameter) in distant galaxies. The co-PIs have assembled the definitive sample of z=1.5-2.5 star-forming galaxies from the Keck MOSFIRE Deep Evolution Field (MOSDEF) survey. They will use this sample to establish the translation between galaxy emission-line and physical properties, and build and publicly release a software tool for robust modeling of the rest-optical emission-line spectra of distant galaxies all the way back to cosmic dawn (z6). The proposed products will provide a lasting legacy as we enter into a new era for near-IR spectroscopy with great observatories in space.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.