Origin and Evolution of Quasar Absorption Systems and Primordial Galaxies

我们通过关注类星体吸收系统来研究星系的形成/演化过程。特别地，我们探索了宇宙中含有最多中性氢的阻尼Lyman-alpha（DLA）吸收体系的演化。具体来说，我们的目标是揭示中性氢气的质量和空间分布，从而产生dla，目的是对星系演化的早期阶段进行限制。主要结果如下：(1)在低红移（z~0）， DLA星系（典型尺寸~3 kpc）的HI柱密度与DLA系统一样高，对中性氢质量为10^8 M（太阳）的HI选择星系的总体有显著贡献。我们发现HI气体的横截面与HI质量之间有紧密的相关性。这个基于我们的理论模型的结果与盲射电观测是一致的。(2)在高红移（z >2）下，dla与星系早期恒星形成区域的气体有关(e。例如，莱曼- α发射器)演化。我们使用自适应光学系统对DLA星系进行巡天的结果限制了恒星形成速率的上限为20 M（太阳）yr^-1。需要对DLA星系进行盲射电和光学/红外巡天，以统计上显著的样本量为基础进行进一步的调查。

We have investigated galaxy formation/evolution processes by focusing on quasar absorption systems. In particular, we have explored the evolution of Damped Lyman-alpha(DLA) absorption system which contains most amount of neutral hydrogen in the universe. Specifically, we aim to reveal the mass and spatial distribution of neutral hydrogen gas, giving rise to DLAs, in a purpose to put constraints on an early stage of galaxy evolution.Our main results are as follows:(1) At low redshift(z～0), DLA galaxies(typical size～3 kpc), where the HI column densities are as high as those of DLA systems, contribute significantly to the population of HI-selected galaxies at neutral hydrogen mass 10^8 M(solar). We find a tight correlation between cross sections of HI gas and HI masses. This result based on our theoretical models is consistent with the blind radio observations.(2) At high redshifts(z> 2), DLAs are associated with gas in star-forming regions under an early stage of galaxy(e. g., Lyman-alpha emitter) evolution. Our result of DLA galaxy surveys using the adaptive optics system puts constraint on an upper limit of the star formation rates of 20 M(solar) yr^-1.Further investigation based on statistically significant sample size is required by carrying out both blind radio and optical/infrared surveys for DLA galaxies.