First Light In The Universe: Probing the End Of The Dark Ages

AST 0205738马道在当前流行的宇宙学假设中，在非常早期，原星系晕中的气体质量与现在的矮椭圆星系相当，经历了快速冷却和碎裂。这些碎片形成了大质量恒星，这些恒星又合成了重元素，并爆炸成II型超新星，丰富了周围的介质。 然后，这些亚银河系恒星系统产生紫外线辐射和机械能，将宇宙中的大部分氢重新加热和重新电离。 在这些关键的形成阶段期间和之后不久，宇宙的历史记录在热状态，电离度和遍布星系际介质（IGM）的化学成分中。在整个结构形成的时期，IGM在重力的影响下变成了clusional，并作为气体的来源，在亚星系碎片中吸积，冷却和形成恒星，并作为富含金属的物质，能量和辐射的汇。因此，对高红移宇宙的气体和恒星成分的研究为这个时代提供了宝贵的洞察力，以及控制一些最早形成的宇宙结构的坍缩，冷却和演化的基本过程。这一理论项目将在当前星系形成理论的范围内研究第一道光的时代、原星系系统的天体物理学、星系际介质和类星体吸收体。它将集中在这些相互关联的领域中的一系列关键问题：（1）宇宙学再电离，（2）第一次光的时代，和（3）原星系晕，SN驱动的风，和IGM的金属富集。一个协调的方法将被追求，涉及控制物理过程的理论研究，并在当前的结构形成的范例，其影响的直接数值模拟。该计划的结果应有助于规划未来的大型观测设施，例如加州极大望远镜、低频阵列、平方公里阵列和下一代太空望远镜。*

AST 0205738MadauIn currently popular cosmological scenarios at very early times, the gas within protogalactic halos with masses comparable to those of present-day dwarf ellipticals experienced rapid cooling and fragmentation. These fragments formed massive stars , which in turn synthesized heavy elements, and exploded as Type II supernovae, enriching the surrounding medium. These subgalactic stellar systems then generated the ultraviolet radiation and mechanical energy that reheated and reionized most of the hydrogen in the cosmos. The history of the Universe during and soon after these crucial formative stages is recorded in the thermal state, ionization degree, and chemical composition of the all-pervading intergalactic medium (IGM). Throughout the epoch of structure formation, the IGM becomes clumpy under the influence of gravity, and acts as a source for the gas that accretes, cools, and forms stars within subgalactic fragments, and as a sink for the metal enriched material, energy, and radiation which they eject. The study of the gaseous and stellar content of the high-redshift Universe thus provides invaluable insight into this era and the basic processes that govern the collapse, cooling, and evolution of some of the earliest formed cosmological structures. This theoretical project will study the epoch of .first light, the astrophysics of protogalactic systems, the intergalactic medium and quasar absorbers in the context of current theories of galaxy formation. It will focus on a series of critical questions in each of these interrelated areas: (1) cosmological reionization, (2) the epoch of first light, and (3) protogalaxy halos, SN-driven winds, and the metal enrichment of the IGM. A coordinated approach will be pursued involving theoretical studies of the controlling physical processes, and direct numerical simulation of their effects within the current paradigm for structure formation. The results of this program should aid in the planning for future large observational facilities such as the California Extremely Large Telescope, the Low Frequency Array, the Square Kilometer Array, and the Next Generation Space Telescope.***