Exploring the Far Distant Universe by Using Quasars as a Probe

利用类星体吸收线系统的III柱密度分布和数密度演化规律等观测数据，研究了年轻星系的演化特征和红移z = 0.3 - 4的漫射紫外通量。在这个研究计划中，我集中在以下两类：（1）CIV吸收线系统作为星系晕的探测器，（2）三种HI吸收系统作为星系际云的探测器。主要结论如下：对于第一类，利用观测资料研究了气晕的动力学行为、重元素丰度的增长率和紫外漫辐射通量的时间变化。因此，我得出结论，在红移z = 3到2的过程中，晕迅速膨胀，重元素丰度迅速增加。另一方面，我发现漫射紫外线通量在这个时期是恒定的。这些结论表明，年轻的星系是 关于我们 O在星星形成过程中非常活跃，由于恒星强烈的能量喷射，气体晕动态膨胀到100 kpc。对于第二类，我提出了三种III类吸收系统的统一模型，它们是莱曼α森林、莱曼极限系统和阻尼莱曼α线系统。基本模型是一个迷你晕，这是一个星系间的云，由冷暗物质的引力限制。这种微晕被电离并被漫射的紫外线通量加热。因此，如果漫射紫外线通量随时间变化，就会驱动微晕的演化。在微晕的包层中，气体高度电离，被探测为莱曼α森林。在中心部分，紫外光通量衰减，气体保持中性。该区域被观察为莱曼极限系统或阻尼莱曼α线系统。大质量微晕坍缩并演化为星系，这是第一类吸收系统，因此，我认为整个吸收线系统都是在冷暗物质主导的宇宙中再现的。少

By utilizing the observational data such as III column density distribution and number density evolution laws of absorption line systems of quasars, I investigated the evolutionary features of young galaxies and diffuse UV flux at the red shifts of z = 0.3 - 4. In this research project, I concentrated to the following two categories : (1) CIV absorption line systems as a probe of galactic halos, and (2) three kinds of HI absorption systems as a probe of intergalactic clouds. Main conclusions are as follows.As for the first category, I studied the dynamical behavior of a gasecous halo, the increasing rate of heavy element abundances and the time variation of diffuse UV flux utilizing the observational data. As a result, I concluded that the gaecous halo is rapidly expanding and the heavy element abundances are increasing fast during the red shift z = 3 to 2. On the other hand, I found the diffuse UV flux to be constant in this epoch. These conclusions indicate that young galaxies were s … More o active in star formation and gaseous halos dynamically expand to 100 kpc due to the intense energy ejection from stars. At the same time, the emission of UV light from galaxies largely contributes to the diffuse UV background.As for the second category, I proposed a unified model for three kinds of III absorption systems, which are the Lyman alpha forest, Lyman limit systems and damped Lyman alpha line systems. The fundamental model is a minihalo which is an intergalactic cloud confined by the gravity of cold dark matter. This minihalo is ionized and heated up by the diffuse UV flux. Therefore, if the diffuse UV flux varies in time the evolution of minihalos is driven. In the envelope of a minihalo the gas is highly ionized and it is detected as the Lyman alpha forest. In the central part the UV flux is attenuated and the gas keeps in neutral. This region is observed as an Lyman limit system or damped Lyman alpha line system. Massive minihalos will collapse and evolve to galaxies, which are detected as the absorption systems of the first category.Accordingly, I concluded that the whole absorption line systems are reproduced under the cold dark matter dominated universe. Less