Study of Galaxy Evolution by Utilizing Absorption Systems of Quasars

类星体吸收系统的物理性质及其演化特征已被广泛研究，特别是莱曼α森林和金属吸收线，对于莱曼α森林，从引力透镜效应、微晕的动力学演化、z = 0-1处HST结果与漫射紫外背景时间变化规律以及小晕与普遍星系际介质相互作用的关系进行了解释。结果表明：（1）随着z的减小，漫射紫外光通量在z < 2时迅速减小，在z > 2时增大或保持不变。(2)根据这一扩散紫外通量的演化规律，作为莱曼α森林模型的微晕在z > 2处随时间膨胀，在z < 2处随时间收缩。(3)由于与普遍星系际介质的动力学相互作用，小晕中的HI气体很容易被扫出而被探测漏失。这就解释了为什么莱曼阿尔法前锋 ...更多信息 对于金属线系统，在一个简单的巨晕原星系模型的基础上，考虑到原星系中年轻恒星的紫外辐射通量和宇宙漫射紫外背景，计算了C、Si、Mg、O和H等离子的柱密度。为了再现CIV极限系统和莱曼极限系统的观测特征，本文导出了原星系晕中各紫外通量的强度和光谱指数以及气体分布规律。除了这些吸收系统模型外，还考察了是否需要宇宙学常数来再现观测到的各离子的数密度及其演化规律。结果表明，宇宙学常数对MgII系统的观测数密度行为是有帮助的，但在目前稀疏的数据下，对其他吸收系统不是必需的。利用HST观测附近的吸收系统对于更清楚地给出宇宙学常数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