Origin and Evolution of Quasar Absorption Systems and Primordial Galaxies

我们已经研究了星系的形成/演化过程中，专注于类星体吸收系统。特别是，我们探讨了宇宙中中性氢含量最多的阻尼莱曼α（DLA）吸收系统的演化。我们的主要结果如下：（1）在低红移（z~0）下，HI柱密度与DLA系统一样高的DLA星系（典型大小为3 kpc）对HI选择星系的星族分布有显著贡献，其中性氢质量为10^8 M（太阳）。我们发现HI气体的横截面和HI质量之间有紧密的相关性。基于我们的理论模型的结果是一致的盲无线电观测。(2)在高红移（z> 2）时，DLAs与星系早期阶段（例如：例如，在一个实施例中，莱曼-α发射体）演化。我们利用自适应光学系统对DLA星系进行的巡天观测结果限制了星星形成速率的上限为20 M（太阳）年^-1。

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.