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A Study of Large-Scale Structures in the High-Redshift Universe with Spectroscopic Observations of QSO

利用 QSO 光谱观测研究高红移宇宙中的大尺度结构

基本信息

批准号：
10640233
负责人：
TAKADA-HIDAI(HIDAI) Masahide
金额：
$ 2.24万
依托单位：
TOKAI UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

As for the observational study, the high dispersion spectra of the triplet QSO system (KP 76, 77, 78) obtained with Keck HIRES were analyzed. W-e measured values of redshift (z), column density (N (H) or N (metal)), and Doppler parameter (b) of Ly-α and metallic absorption lines in each Ly-α forest using the VPFIT code. The total numbers of measured Ly-α line are 153, 263, and 215 in KP76, 77, and 78, respectively. Among them, metallic line systems associate with 8, 8, and 13 Ly-α lines, respectively. Based on these measurements, we obtained the following main results : (1) Inspecting N (H) vs. z relation, the low-density regions with logN (H)<14 are found to exist at z=2.08 and 2.38, of which size along line of sight are 11-17 h^<-1> Mpc. Also the low-density region at z=2.50 is suggested. These sizes are not explained by the simulations based on CDM model described below. (2) The number density per unit z (dn/dz) shows a trend of strong evolution for log N (H)>14, while that of weak … More evolution for log N (H)=13-14. (3) The Log N (H) of Ly-α lines with metallic line systems is found to be larger than 14 in all cases. (4) The Ly-α lines with b>150 km/s are detected, which is consistent with theoretical simulations. At present we are preparing for the paper of these results.As for theoretical studies, we investigated the formation of large-scale structures and evolution of metal pollution in intergalactic medium based on the 3-dimensional cosmological numerical simulations for CDM models, which are calculated by taking account of effects of galaxy formation, supernova explosion, and galactic wind. The main results are : (1) The distribution of metallic gas is found to be very inhomogeneous and exist along the high-density regions of filamentary structure, in which galaxy is formed. (2) The metallic pollution does not occur in low-density regions. (3) O VI lines show a broad feature like Ly-α lines, so it is worth trying to detect O VI lines in Ly-α forest. (4) The simulation prediction of the observed low-density regions will be made by a future study. Less

在观测研究方面，分析了用Keck hires得到的三重态类星体系统(Kp76，77，78)的高色散谱。W-e测量了Ly-α和各Ly-α森林金属吸收谱线的红移(Z)、柱密度(N(H)或N(金属))和多普勒参数(B)。在KP76、77和78中测得的Ly-α谱线总数分别为153条、263条和215条。其中，金属线系分别与8条、8条和13条Ly-α谱线伴生。在此基础上，我们得到了以下主要结果：(1)考察N(H)与z的关系，发现在z=2.08和2.38处存在具有logn(H)和lt；14的低密度区，其视线尺寸为11-17h；并提出了z=2.50时的低密度区。下文所述的基于清洁发展机制模型的模拟没有解释这些大小。(2)单位z的数密度(dN/dz)对数N(H)和Gt；14表现出较强的演化趋势，而较弱的…则表现出较强的演化趋势Log N(H)=13-14的更多演化。(3)金属线系Ly-α线的对数N(H)在所有情况下都大于14。(4)探测到了b&gt；150 km/S的Ly-α谱线，与理论模拟结果一致。目前，我们正在准备这些结果的论文。在理论研究方面，我们基于三维宇宙数值模拟的CDM模型研究了星际介质中大尺度结构的形成和金属污染的演化，该模型考虑了星系形成、超新星爆炸和银河系风的影响。主要结果是：(1)金属气体的分布非常不均匀，沿形成星系的丝状结构的高密度区域存在。(2)低密度区不存在金属污染。(3)O-VI线具有与Ly-α线相似的广泛特征，因此值得尝试在Ly-α森林中检测O-VI线。(4)对观测到的低密度区的模拟预报有待进一步研究。较少