Disk galaxies in a cosmological context

星系是宇宙的基石。 我们的太阳（一颗星星）围绕着一个由大约4000亿颗恒星组成的盘状系统--一个被称为银河系的螺旋星系--运行。 我们的银河系只是可观测宇宙中的一千亿分之一。 了解星系的起源以及它们如何出现和演化是宇宙学研究的主要目标。 该提案的重点是在拉姆达-冷-暗物质宇宙学模型的背景下理解盘星系的演化-目前解释宇宙结构起源的范式。 在这个模型中，星系是由恒星和气体组成的有组织的系统-我们可以看到的东西-以及一种由一种称为暗物质的神秘物质组成的称为光环的不可见成分。 暗物质晕解释了星系的旋转运动，是宇宙学理论的重要组成部分。 盘状星系占银河系总人口的大多数。 当它们的形态被详细量化时，它们以螺旋图案、条形（细长的中心结构）和边缘的微妙翘曲的形式显示出奇妙的结构。 这些结构的特征似乎也随着时间的推移而变化，过去的棒星系较少，螺旋图案更受干扰。 造成这些特征的物理机制是驱动和激发它们形成的重力。 恒星盘和气体与暗晕之间的引力相互作用是主要的驱动力。 在这个提议中，我们使用并行超级计算机上的数值实验来模拟这些物理过程。 我们使用粒子建立真实的星系模型，并计算它们的运动方程，以根据已知的引力定律模拟恒星和暗物质的相互作用。 在这个数值实验室中，我们可以测试各种假设的起源的螺旋结构和酒吧的结果与周围的暗物质晕的相互作用，从而探索宇宙学范式的一致性与观察到的星系的属性。 这些过程的计算机动画将数十亿年的动力学过程转化为星系演化的直观呈现。

Galaxies are the building blocks of the universe. Our sun (a star) is in orbit around a large disk-shaped system of about four hundred billion stars - a spiral galaxy known as the Milky Way. Our Milky Way is just one in a 100 billion that we can count in the observable universe. Understanding the origin of galaxies and how they emerge and evolve is a primary goal in cosmological research. This proposal focuses on understanding the evolution of disk galaxies within the context of the Lambda-Cold-Dark-Matter cosmological model - the current paradigm for explaining the origin of structure in the universe. In this model, galaxies are organized systems of stars and gas - stuff we can see - and an invisible component called the halo made of a mysterious substance called the dark matter. The dark matter halo explains the rotational motion of galaxies and is an essential component of cosmology theory. Disk galaxies represent the majority of the total galactic population. When their morphology is quantified in detail, they show wonderful structure in the form of spiral patterns, bars (elongated central structures) and subtle warping at the edges. The character of these structures also seems to be varying with time with fewer barred galaxies and more disturbed spiral patterns in the past. The physical mechanism responsible for most of these features is gravity that drives and excites their formation. The gravitational interaction between the disk of stars and gas with the dark halo is the primary driver. In this proposal, we model these physical processes using numerical experiments on parallel supercomputers. We build realistic models of galaxies using particles and compute their equations of motion to simulate the interaction of the stars and dark matter according to the known laws of gravity. In this numerical laboratory, we can test various hypotheses for the origin of spiral structure and bars as the result of the interaction with surrounding dark matter halo and so explore the consistency of the cosmological paradigm with the observed properties of galaxies. Computer animations of these processes translate billions of years of dynamical processes into an intuitive presentation of galaxy evolution.