NSF-BSF: The Physics of Multiphase Gas Streams feeding Galaxies from the Cosmic Web

在过去的二十年里，星系形成的一幅连贯的画面已经出现，气体从星系间介质（IGM）通过一个由狭窄的细丝和薄片组成的网络流入巨大的暗物质晕，这些网络共同构成了“宇宙网”。这种气体的吸积为恒星形成提供燃料，决定了盘状星系的角动量和大小，并导致了湍流和盘状星系的不稳定性。如果不详细了解这个吸积过程，我们就不能完全了解星系的演化。然而，这种流入的数值模拟极具挑战性。这个研究小组将通过一套扩展的宇宙磁流体动力学模拟来解决这些缺点，这些模拟旨在解决细丝和IGM，以准确地模拟它们的演化，并探索星系如何从形成的最早阶段被滋养的详细物理。这项工作将为两名研究生提供指导和培训。该团队还将为耶鲁大学的科学之路项目创建一个宇宙学模块，并为高中生提供为期两周的免费暑期STEM项目。所提出的模拟将在所有相关尺度上解决气体的多相结构，从mpc大小的宇宙薄片和细丝到在流和流源盘内形成的致密团块（数十秒差距）的气体。这样一个全面的理论分析有望在宇宙学背景下重塑对星系形成的理解，并加深我们对多相等离子体物理学的理解。它也非常及时地帮助解释星系周围气体、莱曼α斑点、莱曼α森林和无金属莱曼极限系统的当前和即将到来的观测数据。此外，本研究旨在提高对高z盘状星系如何获得角动量以及触发湍流和维持剧烈不稳定性的机制的理解。作为这项研究的一部分，所有的模拟都将公开。该团队还将建立分析模型，以概括他们的发现，并阐明星系形成的物理原理。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Over the past two decades, a coherent picture of galaxy formation has emerged whereby gas flows into massive dark matter halos from the Intergalactic Medium (IGM) via a network of narrow filaments and sheets that together comprise the "cosmic web”. This gas accretion supplies fuel for star formation, sets the angular momentum and size of disk galaxies, and drives turbulence and disk instabilities. We cannot fully understand galaxy evolution without a detailed understanding of this accretion process. However, numerical simulations of this inflow are extremely challenging. This research team will address these shortcomings through an extended suite of cosmological magneto-hydrodynamical simulations designed to resolve the filaments and IGM to accurately model their evolution and explore the detailed physics of how galaxies are fed from their earliest stages of formation. This work will provide mentoring and training for two graduate students. The team will also create a cosmology module for Yale's Pathway to Science program and run a free two-week summer STEM program for high school students. The proposed simulations will resolve the multiphase structure of gas over all the relevant scales, from the Mpc-sized cosmic sheets and filaments to the dense clumps (tens of parsecs) of gas that form within the streams and the stream-fed disks. Such a comprehensive theoretical analysis promises to reshape the understanding of galaxy formation in a cosmological context as well as deepen our understanding of the physics of multiphase plasmas. It is also highly timely to aid in interpreting current and upcoming observational data of the gas around galaxies, Lyman-alpha blobs, the Lyman-alpha Forest, and metal-free Lyman limit systems. In addition, this study aims to improve the understanding of how high-z disk galaxies acquire their angular momentum and which mechanisms are responsible for triggering turbulence and maintaining violent instabilities. All simulations run as part of this study will be made publicly available. The team will also build analytic models that encapsulate their findings and elucidate the physics of galaxy formation.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.