When are Disk Galaxies First Assembled?

盘状星系何时首次组装？

• 批准号: 1815251
• 负责人: Susan Kassin
• 金额: $ 40.3万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-15 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1815251&HistoricalAwards=false
• 关键词: When; Disk; Galaxies; First; Assembled

Today nearly all galaxies that are actively forming stars are disk galaxies. Our own galaxy, the Milky Way, is one example. Disk galaxies are composed of a thin and symmetric rotating disk of stars and gas. This project will determine when disk galaxies first formed in significant numbers. Researchers will measure the fraction of disk galaxies over the last 10 billion years. These fractions will be compared with two theoretical models for disk formation in order to understand how disks form. In addition, simulated observations will be made of theoretical models of galaxies. A large set of these simulated observations will be used to train a classification algorithm to automatically distinguish between disks and colliding galaxies, which are easily mistaken for disks. The resulting algorithm will then be applied to existing observations of hundreds of galaxies in order to identify the fraction of disks. This project will also establish an "Astro Scholars" annual week-long intensive mini-course targeted at students in local Historically Black Colleges and Universities (HBCUs). Scholars will receive financial support. Monthly follow- up after the summer program will extend the impact of the program for 6 months.Current measurements of the fraction of disk galaxies are inaccurate. They do not take into account that some colliding galaxies can appear to be disk galaxies. To measure the fraction of disks over time, researchers will create disk criteria. These criteria will determine if a given observation indicates a disk or colliding galaxies. The criteria will be created with models of galaxies using publicly available suites, VELA and FIRE, of computer simulations. Researchers will simulate observations with mock catalogues that will be compared directly to observations, taking into account the blurring effects of the Earth's atmosphere. Researchers will create disk criteria by comparing the intrinsic states of the simulations (disk or collision) with the simulated observations. These criteria will indicate the probability an observation is a disk or colliding galaxies. These criteria will be applied to KMOS3D integral field unit observations of nearly 600 galaxies. They will measure the fraction of star-forming galaxies which are disks over time. The disk criteria will serve as a powerful tool for recent (and ongoing) large surveys of galaxy kinematics. They will be key for next-generation surveys that will push observations of galaxy kinematics to the very early universe, when the first galaxies formed, and galaxy collisions were even more frequent.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.

今天，几乎所有正在活跃地形成恒星的星系都是盘状星系。我们的银河系就是一个例子。盘星系是由一个薄而对称的旋转的恒星和气体盘组成的。该项目将确定盘状星系何时首次大量形成。研究人员将测量过去100亿年中盘状星系的比例。这些分数将比较两个理论模型的磁盘形成，以了解磁盘的形式。此外，还将对星系的理论模型进行模拟观测。这些模拟观测的一个大集合将用于训练分类算法，以自动区分盘和碰撞星系，这些星系很容易被误认为是盘。由此产生的算法将被应用到数百个星系的现有观测，以确定磁盘的分数。该项目还将设立一个“天文学者”年度为期一周的密集迷你课程，对象是当地历史上的黑人学院和大学的学生。学者将获得财政支持。夏季计划后的每月后续行动将延长该计划的影响6个月。目前对盘星系比例的测量是不准确的。他们没有考虑到一些碰撞的星系可能看起来是盘状星系。为了测量随时间推移的磁盘比例，研究人员将创建磁盘标准。这些标准将决定一个给定的观测是否表明一个磁盘或碰撞星系。这些标准将使用公开可用的计算机模拟套件VELA和FIRE与星系模型一起创建。研究人员将用模拟目录模拟观测，这些目录将直接与观测结果进行比较，同时考虑到地球大气层的模糊效应。研究人员将通过比较模拟的内在状态（磁盘或碰撞）与模拟观察来创建磁盘标准。这些标准将指示观测是盘或碰撞星系的概率。这些标准将被应用到近600个星系的KMOS 3D积分场单位观测。他们将测量随着时间的推移，恒星形成星系中圆盘的比例。盘标准将作为一个强大的工具，最近（和正在进行的）大型调查星系运动学。他们将是下一代调查的关键，这些调查将把星系运动学的观测推到非常早期的宇宙，当第一个星系形成时，星系碰撞更加频繁。这个奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。