On the Relation Between Galaxies and Dark Matter Halos

暗物质约占总质量的85%，是宇宙结构形成的主要驱动力，但目前暗物质的性质尚不清楚。星系在恒星和气体中含有可见的重子物质，嵌入了巨大的暗物质光晕中。(宇宙中的“重子物质”主要由质子和中子以及以这些粒子为基础的化学元素组成。)因此，星系可以作为可见的探测器，研究暗物质在宇宙大尺度结构形成和演化中的作用，这是现代宇宙学的一个基本问题。这个项目旨在提高我们对星系组合以及暗物质和重子物质之间关系的理解。研究人员将扩展和改进用于理解星系和暗物质晕之间联系的模拟和统计工具。他们将研究环境和宇宙时间对暗物质晕中星系性质的影响。他们将创建逼真的模拟星系星表，这对于更好地解释即将到来的大型星系调查是必不可少的。该项目将支持研究生和本科生在研究项目中的指导和积极参与。PI还将扩大与克利夫兰自然历史博物馆天文馆的合作伙伴关系，为本科生实习生提供一个独特的机会，并通过星系调查丰富公众对这门科学的理解。光晕职业建模是解释星系团测量和约束星系与暗物质之间关系的强大理论工具。在这些概率模型中做出的一个标准假设是，暗物质晕的质量完全决定了它所包含的星系的性质。该项目将扩展建模方法，以包括宇宙进化和环境依赖，这是目前缺失的两个关键方面。首先，将使用半解析星系形成模型来研究晕占据模型的演化。我们将使用半解析模型和流体力学模拟来探索这些模型对星系大尺度环境的依赖性。这两项研究随后将结合起来考察环境演变的趋势和对环境的依赖程度。最后，将这种扩展的建模方法应用于SDSS的模拟数据和真实数据。

Dark matter, which accounts for about 85% of all mass, is the dominant driver of structure formation in the Universe, but the nature of dark matter currently is unknown. Galaxies, containing visible, baryonic matter in stars and gas, are embedded in vast dark matter halos. ("Baryonic matter" in the Universe primarily consists of protons and neutrons, and the chemical elements based on those particles.) Galaxies, therefore, can be used as visible probes of dark matter's role in the formation and evolution of large-scale structure in the Universe, a fundamental problem in modern cosmology. This project aims to improve our understanding of galaxy assembly and the relationship between dark and baryonic matter. The researchers will expand and improve simulations and statistical tools used to understand the connection between galaxies and their dark matter halos. They will study the influence of environment and cosmic time on the properties of galaxies in dark matter halos. They will create realistic mock galaxy catalogs that will be essential for a better interpretation of upcoming large galaxy surveys. The project will support the mentoring and active involvement of both graduate and undergraduate students in the research program. The PI will also expand a partnership with the planetarium at the Cleveland Museum of Natural History, providing a unique opportunity for undergraduate interns and enriching the public understanding of the science from galaxy surveys.Halo occupation modeling is a powerful theoretical tool to interpret galaxy clustering measurements and constrain the relation between galaxies and dark matter. A standard assumption made in these probabilistic models is that the mass of the dark matter halo fully determines the properties of the galaxies contained in it. This project will extend the modeling approach to include cosmic evolution and environmental dependence, two crucial aspects that are currently missing. First, the evolution of the halo occupation models will be studied using semi-analytic galaxy formation models. The dependence of these models on the large-scale environment of the galaxies will be explored using both semi-analytic models and hydrodynamical simulations. These two studies will then be combined to examine the evolution of the environment trends and the environment dependence of the evolution. Finally, this extended modeling approach will be applied on simulated and real data from SDSS.