Study of Galaxy Evolution by Utilizing Absorption Systems of Quasars

对类星体吸收系统的物理性质及其演化特征进行了研究，重点研究了Lyman α森林和金属吸收谱线。对于Lyman alpha森林，从引力透镜效应、微晕的动力学演化、z = 0-1时HST结果与漫射紫外背景时间变化规律的解释以及微晕与普遍星系际介质的相互作用等几个方面进行了研究。结果表明：(1)漫射紫外通量强度在z < 2处迅速减小，在z < 2处随z的减小而增大/保持恒定。(2)根据这种漫射紫外通量的演化规律，作为Lyman α森林模型的微晕在z < 2处随时间扩张，然后在z < 2处变为收缩。(3)由于与普遍存在的星系际介质的动力学相互作用，微晕中的HI气体很容易被扫出而在探测中被遗漏。这就解释了为什么Lyman alpha before…More st没有表现出任何聚类特征，因为如果聚类，小光晕会迅速被破坏。对于金属线系统，基于具有巨晕的原星系的简单模型，考虑原星系中年轻恒星的紫外通量以及漫射宇宙漫射紫外背景，计算了C、Si、Mg、O和H各离子的柱密度。为了综合再现CIV和Lyman极限系统的观测特征，推导了原星系晕中各紫外线通量的强度和光谱指数以及气体分布规律。这与其他原因决定的结果是一致的。除了这些各自的吸收系统模型外，还检验了是否需要宇宙学常数来再现观测到的每个离子的数密度及其演化规律。结果表明，在现有的稀疏数据中，宇宙学常数对观测到的MgII系统的数密度行为有帮助，而对其他吸收系统则不是必需的。利用HST观测附近的吸收系统对于给出关于宇宙常数更清晰的结论是至关重要的。少

The physical properties and their evolutionary characteristics of quasar absorption systems have been studied, especially, in focusing to the Lyman alpha forest and metallic absorption lines.As for the Lyman alpha forest, several aspects such as the gravitational lensing effects, the dynamical evolution of minihalos, the explanation of HST results at z = 0-1 in relation to the time variation laws of diffuse UV background and interactions of minihalos with pervasive intergalactic medium. The conclusions are : (1) The intensity of diffuse UV flux decreases rapidly at z < 2 and increases/keeps constant at z > 2 with decreasing z. (2) According as this evolution law of diffuse UV flux, the minihalo as a model of Lyman alpha forest expands at z > 2 and then changes to contraction at z < 2 with time. (3) Due to the dynamical interactions with pervasive intergalactic medium, the HI gas in a minihalo is easily swept out and missed in detection. This explains the reason why the Lyman alpha fore … More st does not show any clustering features because minihalos are swiftly destructed if clustered.As for the metallic line systems, based upon a simple model for proto-galaxies with giant halos, the column densities of respective ions of C, Si, Mg, O and H have been calculated in consideration of the UV flux from young stars in a proto-galaxy as well as the diffuse cosmic diffuse UV background. For reproducing the observed characteristics of CIV and Lyman limit systems altogether, the intensity and spectral index of each UV flux and gas distribution laws in a protogalactic halo are deduced. These are consistent with those determined by other reasons.In addition to these respective models of absorption systems, it is examined whether the cosmological constant is needed to reproduce the observed number density and its evolution law of each ion. The result indicates that the cosmological constant is helpful for the observed number density behavior of MgII systems but not necessary for other absorption systems within present sparse data. It is crucial to observe nearby absorption systems by using the HST for giving much clearer conclusions on the cosmological constant. Less