Cosmological Simulations of the Formation of Dark Matter Cores and Bulgeless Galaxies

理解影响星系形成和演化的物理过程是现代天体物理学的一个基本问题。该项目将在一个完整的冷暗物质（CDM）宇宙学背景下运行高分辨率和物理细节的模拟，重点研究星系中心的这个问题。这项工作的重点是CDM模型的预测与观测证据之间的三个密切相关的差异：1)小星系中心的暗物质核心，2)大部分无凸起的矮星，以及3)存在非常小（伪）凸起的大质量盘状星系。这些模拟有三个共同的特征：1)对恒星形成的简单但物理动机的描述，2)由超新星和超大质量黑洞的能量反馈驱动的气体流出，3)由紫外线光子猝灭的恒星形成。这些模拟将在整个哈勃时间内解析出精确到50秒差距的星系内部结构。这种方法将直接将n体模拟中粒子的空间分布和物理特性与实际测量的真实星系的数量联系起来，使用软件“观察”模型，包括物理效应以及仪器的已知特性，以创建真实的人工数据集。这个团队已经使用这种方法获得了具有暗物质核心的无凸起星系形成的开创性结果，并模拟了一组宇宙星系，同时再现了光度-大小关系，阻尼Lyman α系统的丰度，以及HI Tully-Fisher关系。这项新工作的具体目标包括了解气体流出如何在星系中心产生暗物质核心，并在一系列星系质量、合并和恒星形成历史上预测它们的大小，了解气体流出、合并和星系中心区域的各种动态不稳定性在恒星凸起和伪凸起的产生或抑制中的作用，并预测星系中重子质量分布的可观测光度和运动学性质。PI将与他所在机构资助的天文学预专业项目（Pre-MAP）合作，该项目帮助代表性不足的学生过渡到大学，并可能过渡到天文学专业，为他们提供学术建议和一对一的指导，同时指导他们完成研究项目。本研究将为Pre-MAP学生提供研究项目，并为与该计划相关的本科生提供辅导和支持。

ABSTRACTAST-1108885GovernatoUnderstanding the physical processes that shape the formation and evolution of galaxies is a fundamental question in modern astrophysics. This project will run simulations with high resolution and physical detail in a full Cold Dark Matter (CDM) cosmological context, studying this problem with a strong emphasis on galaxy centers. The work focuses on three closely interconnected discrepancies between predictions of the CDM model and the observed evidence for i) dark matter cores at the centers of small galaxies, ii) the large fraction of bulgeless dwarfs, and iii) the existence of massive disk galaxies with very small (pseudo) bulges. The simulations share three common features: i) a simple yet physically motivated description of star formation, ii) gas outflows driven by energy feedback from supernovae and supermassive black holes, and iii) star formation quenching by ultraviolet photons. These simulations will resolve the inner structure of galaxies down to fifty parsecs over the entire Hubble time. This approach will relate directly the spatial distribution and physical properties of the particles in the N-Body simulations to the quantities actually measured for real galaxies, using software to "observe" the models, including physical effects as well as the known properties of instruments, to create realistic artificial datasets.This team has already used this approach to obtain seminal results on the formation of bulgeless galaxies with dark matter cores, and to simulate a cosmological set of galaxies that simultaneously reproduce the luminosity-size relation, the abundance of damped Lyman alpha systems, and the HI Tully-Fisher relation. Specific goals of this new work include understanding how gas outflows create dark matter cores at the centers of galaxies and predicting their size over a range of galaxy masses and merging and star formation histories, understanding the role of gas outflows, mergers and various dynamical instabilities in the central region of galaxies on the creation or suppression of stellar bulges and pseudo bulges, and predicting the observable photometric and kinematic properties of the baryonic mass distribution in galaxies.The PI will collaborate with his institution's funded Pre-Major in Astronomy Program (Pre-MAP), which helps underrepresented students in their transition to college and possibly to an astronomy major, providing them with academic advising and one to one mentorship while guiding them through research projects. The present study will provide research projects for Pre-MAP students and tutoring and support for undergraduates linked to the program.