The Cosmic History of Baryons

重子的宇宙历史

• 批准号: 9802568
• 负责人: David Weinberg
• 金额: $ 24.26万
• 依托单位: Ohio State University Research Foundation -DO NOT USE
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-06-01 至 2002-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9802568&HistoricalAwards=false
• 关键词: Cosmic; History; Baryons

AST 98-02568 David H. Weinberg Dr. Weinberg proposes to work with Dr. Katz (University of Massachusetts) and Dr. Hernquist (University of California, Santa Cruz) to conduct numerical simulations that model the cosmic history of the baryon component of the universe from z ~ 8 to the z=0, with particular attention to the Ly a forest, high redshift galaxies and the distributions of galaxies and intergalactic gas in the local universe. They plan to use TreeSPH - a numerical simulation code that combines a hierarchical tree N-body algorithm for gravitational components with smoothed particle hydrodynamics (SPH) for the gas component. The code now exists in parallel form. According to the leading cosmological theories, the galaxies and large scale structure that we observe today grew by gravitational instability from small-amplitude fluctuations in the early universe. Gravitational clustering of collisionless dark matter drives the evolution of the mass distribution on large scales, but astronomical observations reply almost exclusively on electromagnetic radiation that has been emitted (or in some cases absorbed) by stars or gas. Hydrodynamic simulations, which incorporate the non-gravitational physics that influences the evolution of the cosmic baryon distribution, dramatically enhance the predictive and explanatory power of cosmological theories. Preliminary results from the simulations show that a substantial population of high redshift galaxies is predicted by several variants of the cold dark matter scenario. The team is studying the clustering of Lyman break galaxies in different scenarios. Hydrodynamic simulations show that the low column density Ly a forest arises primarily in diffuse, smoothly fluctuating, intergalactic gas. The physics of this medium is remarkably simple, allowing the simulations to make robust, quantitative predictions given a specified cosmological model. Simulations of high redshift structure, supported by QSO absorption data, indicate that most of t he high redshift baryons reside in the diffuse medium that produces the Ly a forest, with smaller fractions in galaxies and hot gas halos. ***

02568 David H.Weinberg博士建议与马萨诸塞大学的Katz博士和加州大学圣克鲁斯分校的Hernquist博士合作进行数值模拟，模拟从z~8到z=0宇宙中重子成分的宇宙历史，特别关注Ly a森林、高红移星系以及星系和星际气体在局部宇宙中的分布。他们计划使用TreeSPH-一种数值模拟代码，它结合了重力分量的分层树N-Body算法和气体分量的平滑粒子流体动力学(SPH)。代码现在以并行形式存在。根据主要的宇宙学理论，我们今天观察到的星系和大尺度结构是由早期宇宙中的小幅度波动引起的引力不稳定造成的。无碰撞暗物质的引力聚集推动了大尺度质量分布的演变，但天文观测几乎完全根据恒星或气体发射(或在某些情况下吸收)的电磁辐射来回答。流体动力学模拟结合了影响宇宙重子分布演化的非引力物理，极大地增强了宇宙学理论的预测和解释能力。模拟的初步结果表明，冷暗物质情景的几个变种预测了相当数量的高红移星系。该团队正在研究莱曼破裂星系在不同情况下的聚集情况。流体力学模拟表明，低柱子密度的森林主要是由弥漫的、平稳波动的星系间气体形成的。这种介质的物理原理非常简单，允许模拟在给定特定的宇宙学模型的情况下做出可靠的、定量的预测。在类星体吸收数据的支持下，对高红移结构的模拟表明，大多数高红移重子存在于产生Ly a森林的扩散介质中，少数存在于星系和热气晕中。***