Multiwavelength Studies of Galaxy Evolution

星系演化的多波长研究

• 批准号: RGPIN-2015-03851
• 负责人: Webb, Tracy
• 金额: $ 1.6万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=678807
• 关键词: Multiwavelength; Studies; Galaxy; Evolution

***We live in a hierarchically organized universe. Over the past two decades, observational evidence and theoretical predictions have converged on a remarkably successful cosmological model -- cold Dark Matter with a  Dark Energy component -- that describes the formation and evolution of structure at all scales through the gravitational amalgamation of matter. The backbone of this process is  well understood, but the physics on the scales of stars, galaxies and galaxy clusters is very complex and controlled by multiple variables.   This research program seeks to understand these processes and, in particular, the processes which formed galaxies like our own Milky Way.  ***In hierarchical structure formation  small objects (with masses of a million suns - small galaxies) form first after the Big Bang and then combine over time to form the largest objects seen today (reaching masses of a million billion stars).   The act of coalescing galaxies is a violent and complex one which dramatically alters the physical state of the systems. Existing stars are redistributed, new populations of stars are produced in prodigious triggered bursts, and central supermassive black holes grow through infalling matter. Nevertheless, if we study galaxies in the universe today we see tight relationships between their properties which are indicative of underlying global processes.***For example, the mass, shape and overall age of a galaxy is dependent on its local environment.  Massive galaxies, that are elliptical and composed of old stars inhibit dense regions of the universe, with many other galaxies nearby.  Moderate mass galaxies like our own Milky Way, with on-going star formation and spiral structure live in more isolated regions.   My research program wants to understand the reasons behind trends such as these.***Because light takes a finite time to travel, we see distant galaxies  as they existed a long time ago.  We use the world's largest telescopes to observe the most distant galaxies in the universe at a much earlier stage in their formation.  By studying many galaxies at different times and in different environments we can piece together their evolutionary history. Using light emitted at different wavelengths we can measure the amount of stars a galaxy is composed of, the rate at which it is forming new stars, and whether it is growing a supermassive black hole at its center.  Its physical shape often provides clues to the processes it is experiencing - such as a major galaxy merger event.***We study large samples of galaxies in a quest to identify and understand global trends in their evolutionary phases.  Occasionally, we discover a unique object that, if studied in detail can provide a wealth of information on a particular aspect of galaxy formation.  By combining these two distinct approaches we can piece together a picture of how the rich and complex structure we see around us today was formed. *****

我们生活在一个等级森严的宇宙中。在过去的二十年里，观测证据和理论预测都集中在一个非常成功的宇宙模型上——带有暗能量成分的冷暗物质——该模型描述了通过物质的引力融合在所有尺度上结构的形成和演化。这一过程的主干已经被很好地理解了，但是恒星、星系和星系团尺度上的物理是非常复杂的，并且受到多个变量的控制。这个研究项目旨在了解这些过程，特别是形成像我们银河系这样的星系的过程。***在分层结构形成中，小物体（质量为一百万个太阳-小星系）首先在大爆炸后形成，然后随着时间的推移结合形成今天看到的最大物体（达到一百万亿个恒星的质量）。星系合并是一个剧烈而复杂的过程，它极大地改变了系统的物理状态。现有的恒星被重新分配，新的恒星群在巨大的触发爆发中产生，中心的超大质量黑洞通过下落的物质生长。然而，如果我们今天研究宇宙中的星系，我们会看到它们的性质之间的紧密关系，这表明了潜在的全球过程。例如，星系的质量、形状和总体年龄取决于它的局部环境。由老恒星组成的椭圆形大质量星系抑制了宇宙的密集区域，附近还有许多其他星系。中等质量的星系，比如我们的银河系，有持续的恒星形成和螺旋结构，生活在更孤立的区域。我的研究项目想要了解这些趋势背后的原因。因为光的传播需要有限的时间，所以我们看到的遥远星系就像很久以前存在的一样。我们使用世界上最大的望远镜来观察宇宙中最遥远的星系在它们形成的早期阶段。通过研究不同时间和不同环境下的许多星系，我们可以拼凑出它们的进化史。利用不同波长发出的光，我们可以测量一个星系组成的恒星数量，它形成新恒星的速度，以及它是否正在中心形成一个超大质量黑洞。它的物理形状经常为它正在经历的过程提供线索——比如一次重大的星系合并事件。***我们研究了大量的星系样本，以确定和理解它们进化阶段的全球趋势。偶尔，我们会发现一个独特的物体，如果对其进行详细研究，可以提供关于星系形成特定方面的丰富信息。通过结合这两种不同的方法，我们可以拼凑出一幅我们今天所看到的丰富而复杂的结构是如何形成的画面。＊＊＊＊＊