The Dynamical Echoes Of Dark Matter Sub-Structure: In Simulations & In Spirals Out To z ~ 0.1

目前的宇宙学范式包括两种重要而未知的物理实体，即“暗物质”和“暗能量”，它们被用来模拟我们所知道的宇宙。了解暗物质的分布仍然是天文学中最基本的问题之一，也是这个项目的重点。现有的计算机模拟结果与观测结果存在许多差异。与模拟相比，大质量卫星太少了，而且在银河系低纬度地区几乎没有任何银河系卫星。该项目旨在通过研究人员正在进行的通过分析扩展的氢气盘中的扰动来表征星系卫星的工作，提取螺旋星系中暗物质分布的基本信息。向广大受众传播科学成果并促进多样性有利于天文学界和整个社会。该项目将在罗彻斯特理工学院（RIT）进行，该学院历史上主要是一所本科院校。(1)科学中的女性：PI将定期组织与来访的女性研讨会演讲者的会议，目的是收集专业发展方面的建议。Chakrabarti博士还将继续参加“拓展你的视野”项目，该项目旨在吸引中学女生参与科学。(2)计算训练营：每年夏天，PI将为进入研究生提供为期两周的密集计算训练营。这个训练营的目标是作为一个桥梁——提供一个计算天体物理学的介绍，用实践讲座来说明计算的基础知识和天文学的应用。PI将通过IDL和Python的简单示例进行工作，她将鼓励女性和少数民族学生参加训练营，并为进入的学生分配导师。(3)可视化实验室：PI将继续制作星系碰撞的三维动画，这些动画将在RIT的Viz-Lab中展示。3d电影正在成为一种越来越受欢迎的工具，吸引公众，并有效地广泛传播星系演化的研究。PI将执行以下技术任务：(1)银河系：通过将模拟的银河系卫星轨道与HST固有运动和潮汐碎片进行匹配，PI将推导出轨道参数的约束条件，以及银河系卫星的初始恒星（和暗物质）分布。PI将产生与我们银河系的HI和恒星数据一致的模型，这些数据显示在外围有大的涟漪，一个明显的翘曲，以及银河系盘中的垂直波。(2)探测暗物质晕：暗物质晕随着时间的推移而演变，它们可能具有复杂的形状。PI将决定从恒星流推断光晕势对于时变势是否可行。通过解构流体力学宇宙学模拟ERIS， PI将研究卫星的分布以及气体和恒星盘的形态是否代表银河系或局部螺旋。(3)震动和震动局部螺旋：通过模拟宇宙学模拟中与亚晕的大范围接触，并使用蒙特卡洛马尔可夫链分析以统计稳健的方式映射到多个观测约束，PI将生成真实的模拟目录和HI盘及其卫星群的演化历史。(4) HI中的强螺旋透镜：由于SWELLS样本是一个足够低的强螺旋透镜红移样本（z_avg ~ 0.1），显示出可见的相互作用迹象，PI将比较和对比团队的HI分析和引力透镜，以得出暗物质分布的两个独立约束。

The current cosmological paradigm includes two significant and unknown physical entities called "dark matter" and "dark energy," which are used to model the Universe as we know it. Understanding the distribution of dark matter remains one of the most fundamental problems in astronomy and is the focus of this project. There are many discrepancies between dark matter sub-structure in the existing computer simulations and in observations. There are too few massive satellites relative to simulations, and at low Galactic latitudes there are hardly any Milky Way satellites. This project aims to extract essential information on the dark matter distribution in spiral galaxies by building on the investigator's ongoing work in characterizing galactic satellites from analysis of disturbances in extended disks of hydrogen gas.Communicating scientific results to a broad audience and promoting diversity benefits the astronomy community and our society at large. This project will be carried out at Rochester Institute of Technology (RIT), which has historically been primarily an undergraduate institution:(1) Women in Science: The PI will organize regular meetings with visiting women colloquium speakers, with the goal of gathering advice on professional development. Dr. Chakrabarti will also continue participating in the Expanding Your Horizons program, which is geared towards engaging middle school girls in science.(2) Computational Bootcamp: Every summer, the PI will provide a two-week, intensive computational bootcamp geared towards entering graduate students. The goal of this bootcamp is to serve as a bridge---providing an introduction to computational astrophysics, with hands-on lectures that illustrate the basics of computing and applications to astronomy. The PI will work through simple examples in IDL and Python, and she will encourage women and minority students to attend the bootcamp, and assign mentors for entering students.(3) Visualization Laboratory: The PI will continue producing 3-D animations of galaxy collisions, which will be showcased in the Viz-Lab at RIT. Three-D movies are becoming an increasingly popular tool to engage the public and are effective in widely disseminating research on galaxy evolution.The PI will carry out the following technical tasks:(1) The Milky Way: By matching simulated orbits of the Milky Way satellites with HST proper motions and tidal debris, the PI will derive constraints on the orbital parameters, as well as the initial stellar (and dark matter) distribution of the Milky Way satellites. The PI will produce models that are consistent with both the HI and stellar data of our galaxy, which displays large ripples in the outskirts, a prominent warp, and vertical waves in the galactic disk.(2) Probing The Dark Matter Halo: Dark matter halos evolve as a function of time, and they may have complex shapes. The PI will determine if the inference of the halo potential from stellar streams is viable for time-varying potentials. By deconstructing the hydrodynamical cosmological simulation ERIS, the PI will study if the distribution of satellites and the morphology of the gas and stellar disk is representative of the Milky Way or local spirals.(3) Shaking and Rattling The Local Spirals: By simulating a wide range of encounters with sub-halos from cosmological simulations, and mapping to multiple observational constraints in a statistically robust manner using a Monte Carlo Markov Chain analysis, the PI will produce realistic mock catalogs and evolutionary histories of HI disks and their satellite populations.(4) Strong Spiral Lenses in HI: As the SWELLS sample is a sufficiently low redshift sample of strong spiral lenses (z_avg ~ 0.1) showing visible signs of interaction, the PI will compare and contrast the team's HI analysis and gravitational lensing to derive two independent constraints on the dark matter distribution.