CDS&E: The development of open-source software with an application to modeling the formation of globular star clusters

球状星星团是我们宇宙中最古老的天体之一，几十年来，了解它们的起源一直是天体物理学家面临的巨大挑战。 该项目将开发计算机软件，采用一种新的数值方法来进行模拟这些星团形成的计算。 这一新的计算机软件将使管理各种物理应用的天体物理学更好地计算机建模成为可能。 它也将是第一个公开提供的此类软件。 然后，研究人员将使用该软件创建计算机模拟，模拟球状星星集群的形成，他们特别试图了解这些球状集群中多代恒星的明显创造。 该项目的目标将促进美国在物理学领域的领导地位和加强美国网络基础设施的国家利益。 此外，研究人员将通过资助一名研究生参加哥伦比亚大学自然科学项目的博士学位桥梁项目，解决全国少数民族在科学领域代表性不足的问题。 研究人员将在研究项目中对学生进行培训，并在学生科学生涯的早期阶段对学生进行指导。从技术上讲，该项目的第一部分制定了一个系统的计划，以开发一个新的开源移动网格代码。 最近发展的移动网格方法作为一个可行的替代光滑粒子流体动力学和自适应网格细化是一个很有前途的发展。 动网格流体动力学带来了许多理想的功能，包括低扩散的整体流动，伽利略不变性，以及良好的冲击处理。 软件开发使用现代设计和编码技术来生成高效的并行代码，该代码能够使用广泛的物理特性，并且易于使用和修改。 它将在计算密集型部分使用广泛使用的Python语言与Cython（静态Python编译器）相结合。 编码将是模块化的，旨在允许轻松灵活地扩展到代码的所有部分。 这个项目的第二部分是模拟球状星团的形成。 该代码将应用于理解球状星团形成的三部分计划：模拟理想化低金属含量气体云的碎裂和坍缩，以理解全球坍缩和碎裂的相对重要性;（2）利用宇宙学模拟来确定经历快速碰撞流的气体的物理性质，这是将大量气体聚集在一个小区域内形成GC的先决条件;以及（3）探索从拟议的浓缩物质来源流出的气体重新并入第二代恒星的能力。

Globular star clusters are among the oldest objects in our Universe, and understanding their origin has remained a great challenge to astrophysicists for many decades. This project will develop computer software employing a new numerical method to perform the calculations modeling the formation of these clusters of stars. This new computer software will enable better computer modeling of the astrophysics governing a variety of physical applications. It will also be the first such software to be made publicly available. The investigators will then use this software to create computer simulations that model the formation of globular star clusters, and they specifically seek to understand the apparent creation of multiple generations of stars in these globular clusters. This project's goals will advance the national interests of developing US leadership in physics and enhancing the US cyber infrastructure. In addition, the investigators will address the national underrepresentation of minorities in the sciences by funding a graduate student to participate in Columbia University's Bridge to the PhD in the Natural Sciences program. The investigators will train the student in the research program and will mentor the student through the early stages of his or her science career.More technically, the first part of this project lays out a systematic plan to develop a new open source moving-mesh code. Recent development of the moving-mesh method as a viable alternative to smoothed particle hydrodynamics and adaptive mesh refinement is a promising development. Moving-mesh hydrodynamics brings many desirable features including low-diffusion in bulk flows, Galilean invariance, and good shock handling. The software development uses modern design and coding techniques to produce an efficient, parallel code that will be capable of using a wide range of physics and that is easy to use and modify. It will use the widely used Python language combined with Cython (a static Python compiler) in computationally intensive parts. Coding will be modular and designed to allow easy and flexible extension to all parts of the code. The second part of this project is to simulate the formation of globular clusters. The code will be applied to a three-part plan for understanding globular cluster formation: (1) modeling the fragmentation and collapse of idealized low-metallicity gas clouds to understand the relative importance of global collapse and fragmentation; (2) using cosmological simulations to identify the physical properties of gas undergoing rapid colliding flows, a prerequisite to bring together a large amount of gas in a small region for GC formation; and (3) exploring the ability of gas outflows from the proposed sources of enriched material to be re-incorporated into a second generation of stars.