Feeding the Beasts: Shedding light on the formation processes of today's most massive galaxies.

喂养野兽：揭示当今最大质量星系的形成过程。

• 批准号: RGPIN-2020-04606
• 负责人: Webb, Tracy
• 金额: $ 2.99万
• 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: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=714861
• 关键词: Feeding; Beasts; Shedding; light; formation

We have discovered a new - an unexpected - formation mechanism for the most massive galaxies in the universe: Brightest Cluster Galaxies or BCGs. These systems sit at the centre of rich and massive galaxy clusters, held together by the mutual gravity of their components. Although the standard accepted theory indicates that BCGs should assemble the bulk of their stellar mass through the accretion of smaller gas-poor systems (the so-called hierarchical structure formation scenario) the recent results of my team have shown that substantial in-situ star formation occurs in young BCGs. This is a key result since, as an extreme outcome of evolution, these massive systems are sensitive probes of the models of galaxy formation. It is also surprising as it flies in the face of our understanding of how galaxy clusters accrete galaxies: during in-fall into the cluster the galaxies should be stripped of their interstellar medium and be gas poor by the time they merge wit the BCG - thus making star formation impossible. Yet the immense amount of star formation in and around BCGs indicate that large amounts of fuel have been deposited into the centres of these galaxy clusters. Over the next five years, my team will undertake an ambitious observational program to elucidate the nature of the gas deposition and star formation in these systems. Specifically, our objective is to understand what triggered the intense star formation we have measured, what sustains it and what will eventually quench it. This will require an approach the spans the electromagnetic spectrum of light as different processes emit light at different wavelengths. We will employ the newly-online and next generation facilities such as the Atacama Large Millimetre Array and the James Webb Space telescope, as well as established workhorses such as the Gemini 8m optical telescopes and the Jansky Very Large (radio) Array. The program will encompass the three main aspects of galaxy stellar mass assembly: (i) the current or ongoing star formation; (ii) the existing stars, or the historical star formation and; (iii) the molecular gas fuel, or the future star formation. This three-pronged approach will clarify for the first time, the formation mechanisms of these massive beasts and provide new constraints for the models and theory which form the basis of our understanding of massive galaxy evolution.

我们发现了一种新的 - 一种意外的形成机制，用于宇宙中最庞大的星系：最亮的星系星系或BCG。 这些系统位于丰富和庞大的星系簇的中心，由它们的组件的相互重力保持在一起。尽管标准接受的理论表明，BCG应该通过较小的气体贫困系统（所谓的分层结构形成场景）的积聚来组装其恒星质量，但我团队的最新结果表明，在Young BCG中发生了实质性的现场恒星形成。这是一个关键结果，因为作为进化的极端结果，这些巨大的系统是银河形成模型的敏感探针。这也令人惊讶，因为它面对我们对星系簇如何吸收星系的理解：在落入集群的过程中，星系应剥离出星际培养基，并在合并BCG时变得贫穷，从而使恒星形成变得不可能。然而，BCG及其周围及其周围的巨大恒星形成表明，大量燃料已沉积到这些星系簇的中心。 在接下来的五年中，我的团队将开展一项雄心勃勃的观察计划，以阐明这些系统中气体沉积和恒星形成的性质。 具体而言，我们的目标是了解什么触发了我们测量的强烈恒星形成，维持恒星是什么以及最终将淬火的原因。 这将需要一种方法，因为不同的过程在不同的波长下发出光。我们将采用新近的和下一代的设施，例如Atacama大毫米阵列和James Webb太空望远镜，以及已建立的主力，例如Gemini 8M 8M光学望远镜和非常大的（无线电）阵列的Jansky。 该程序将涵盖Galaxy Stellar质量组装的三个主要方面：（i）当前或正在进行的恒星形成； （ii）现有的恒星，或历史恒星形成； （iii）分子气燃料或未来的恒星形成。 这种三管齐下的方法将首次阐明这些巨大的野兽的形成机制，并为模型和理论提供了新的约束，这是我们对大型星系进化的理解的基础。