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: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=612612
• 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.

我们生活在一个有等级组织的宇宙中。在过去的二十年里，观测证据和理论预测已经汇集在一个非常成功的宇宙学模型上-具有暗能量成分的冷暗物质-通过物质的引力合并描述了所有尺度的结构的形成和演化。这一过程的主干是很好理解的，但恒星、星系和星系团尺度上的物理学非常复杂，受多个变量控制。 该研究计划旨在了解这些过程，特别是形成像我们银河系这样的星系的过程。 在等级结构形成中，小物体（质量相当于100万个太阳--小星系）首先在大爆炸后形成，然后随着时间的推移，联合收割机结合形成今天看到的最大物体（质量达到100亿颗恒星）。 星系合并的行为是一种剧烈而复杂的行为，它极大地改变了系统的物理状态。现有的恒星被重新分配，新的恒星群体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，如果我们研究今天宇宙中的星系，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、形状和整体年龄取决于其所在的环境。大质量星系是椭圆形的，由古老的恒星组成，它们抑制了宇宙的密集区域，附近有许多其他星系。中等质量的星系，如我们的银河系，具有持续的星星形成和螺旋结构，生活在更孤立的区域。 我的研究项目想了解这些趋势背后的原因。 由于光的传播时间有限，我们看到的遥远星系是它们很久以前存在的样子。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历史。利用不同波长的光，我们可以测量一个星系所包含的恒星数量、新恒星形成的速度，以及它是否正在中心形成一个超大质量黑洞。它的物理形状往往为它正在经历的过程提供线索--比如一个重大的星系合并事件。 我们研究大量的星系样本，以确定和理解其演化阶段的全球趋势。偶尔，我们会发现一个独特的物体，如果详细研究，可以提供关于星系形成的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看到的丰富而复杂的结构是如何形成的图片。