The Quenching of Star Formation in Disc Galaxies

现代天文学研究的是塑造我们所生活的宇宙的物理过程。近几十年来，天文学家已经意识到，通过使用我们的物理学知识，我们可以解释对夜空的观测，以了解整个宇宙。 这些信息大部分来自对我们宇宙中星系的观测。这些是宇宙的基本组成部分，数十亿颗恒星的巨大集合照亮了物质的潜在分布。我们有一个很好的基本图片，我们看到的星系（包括我们生活的星系）是如何从早期宇宙密度的微小波动开始的，超过140亿年的宇宙历史发展成为我们今天看到的丰富的星系“动物园”。然而，随着我们使用这些星系作为示踪剂对宇宙进行越来越精确的观测，了解我们在这些星系中看到的无数差异变得越来越重要。我们必须问这样的问题：为什么有些人有螺旋结构，而另一些人没有？为什么有些螺旋线显示条纹和圆环，而另一些则没有？为什么有些恒星形成的速度惊人，而另一些则不然？ 我们的提议旨在利用数据对本地宇宙中的星系进行新的调查，目的是更好地了解它们的内部结构。这项名为“MaNGA”的调查将对近10，000个星系的内部结构和运动进行详细观察-几乎是以前任何类似努力的100倍。MaNGA将在每个星系的网格中获取光谱（“宇宙条形码读数”），提供星系内部运动，化学富集甚至恒星年龄的地图。我们将用这些数据来测试为什么螺旋星系停止形成恒星的想法。我们想要测试的主要想法是，星系棒可以帮助加速螺旋星系的老化过程，通过增加星系中心区域的星星形成并帮助建立中央隆起，使它们更快地耗尽星星形成的燃料。我们将用MaNGA关于棒旋星系和无棒旋星系表面恒星年龄的数据来测试这一点，以确定它如何以及是否发生，以及它对整个星系形成的重要性。

Modern astronomy is the study of the physical processes which shape the universe in which we live. Over recent decades astronomers have realised that by using our knowledge of physics, we can interpret observations of the night sky to learn about the universe as a whole. Much of this information has come from observations of the galaxies in our universe. These are the fundamental building blocks of the universe, massive collections of billions of stars which light up the underlying distribution of matter. We have a good basic picture of how the galaxies that we see (including the one we live in) started as tiny fluctuations in the density of the early universe, and over 14 billion years of cosmic history developed into the rich "Zoo" of galaxies we see today. However, as we make more and more precise observations of the universe using these galaxies as tracers, it becomes more and more important to understand all the myriad of differences we see in these galaxies. We must ask things like: Why do some have spiral structure and others not? Why do some spirals show bars and rings and others not? Why are some forming stars prodigiously and others not? Our proposal is aimed at working with data a new survey of galaxies in the local universe, with the goal of better understanding their internal structures. This survey, called "MaNGA" will make detailed observations of the internal structure and motions of almost 10,000 galaxies - almost 100 times larger than any previous similar effort. MaNGA will take spectra ("cosmic barcode readings") in a grid across each galaxy, providing maps of the internal motions, chemical enrichment, and even the ages of the stars in the galaxy. We will use these data to test ideas about why spiral galaxies stop forming stars. The main idea we want to test is that a galactic bar can help accelerate the ageing process of spiral galaxies, causing them to use up their fuel for star formation more quickly by increasing star formation in the central regions of the galaxy and helping to build a central bulge. We will test this with the MaNGA data on the ages of stars across the face of barred and unbarred spiral galaxies in order to determine how and if it happens, and how important it is to galaxy formation as a whole.