THE COSMIC EVOLUTION OF THE METALLICITY DISTRIBUTION OF IONIZED GAS TRACED BY LYMAN LIMIT SYSTEMS
THE COSMIC EVOLUTION OF THE METALLICITY DISTRIBUTION OF IONIZED GAS TRACED BY LYMAN LIMIT SYSTEMS
复制标题
莱曼极限系统追踪电离气体金属度分布的宇宙演化
DOI：
--
复制
发表时间：
2016
期刊：
影响因子：
--
通讯作者：
M. Fumagalli
中科院分区：
文献类型：
--
作者：
N. Lehner;O. JohnM.;Meara;J. Howk;J. Prochaska;M. Fumagalli
我们提出的第一个结果，从我们的KODIAQ Z调查，旨在确定金属丰度分布和物理性质的部分和全部莱曼极限系统（pLLSs和LLSs;），这是探测的星系际介质（IGM）和星系之间的界面区域。我们研究了31个H i选择的pLLS和用Keck/HIRES观测的LLS在背景类星体中的吸收。我们比较了金属离子的柱密度H i和使用光电离模型来评估金属丰度。pLLS/LLS的金属丰度分布与单峰分布一致，峰值为。因此，这些吸收体的金属丰度分布随z显著变化，因为它是双峰的，峰值在和-0.3。在所研究的z ~-4范围内，有相当一部分（25%~ 41%）的pLLS/LLS的金属丰度远低于阻尼Lyα吸收体（DLAs）的金属丰度，这意味着在IGM/星系界面的所有z范围内都存在贫金属、冷、致密的气体。然而，由pLLS和LLS探测的气体很少是原始的，对于pLLS/LLS具有3%-18%的分数。我们发现，在几个pLLS和LLS的金属丰度范围内的C/α增强，其中C/α是2-5倍，在银河系的金属贫乏的恒星或高红移的DLAs在类似的金属丰度。这可能是由于贫金属星系优先将碳喷射到周围环境中造成的。
We present the first results from our KODIAQ Z survey aimed at determining the metallicity distribution and physical properties of the partial and full Lyman limit systems (pLLSs and LLSs; ), which are probed of the interface regions between the intergalactic medium (IGM) and galaxies. We study 31 H i-selected pLLSs and LLSs at observed with Keck/HIRES in absorption against background QSOs. We compare the column densities of metal ions to H i and use photoionization models to assess the metallicity. The metallicity distribution of the pLLSs/LLSs at is consistent with a unimodal distribution peaking at . The metallicity distribution of these absorbers therefore evolves markedly with z since at it is bimodal with peaks at and −0.3. There is a substantial fraction (25%–41%) of pLLSs/LLSs with metallicities well below those of damped Lyα absorbers (DLAs) at any studied z from to –4, implying reservoirs of metal-poor, cool, dense gas in the IGM/galaxy interface at all z. However, the gas probed by pLLSs and LLSs is rarely pristine, with a fraction of 3%–18% for pLLSs/LLSs with . We find C/α enhancement in several pLLSs and LLSs in the metallicity range , where C/α is 2–5 times larger than observed in Galactic metal-poor stars or high-redshift DLAs at similar metallicities. This is likely caused by preferential ejection of carbon from metal-poor galaxies into their surroundings.
DOI：
10.1088/0004-637x/812/2/98
发表时间：
2015-09
期刊：
The Astrophysical Journal
影响因子：
--
作者：
Jimmy;K. Tran;A. Saintonge;Gioacchino Accurso;S. Brough;P. Oliva-Altamirano;P. Oliva-Altamirano
通讯作者：
Jimmy;K. Tran;A. Saintonge;Gioacchino Accurso;S. Brough;P. Oliva-Altamirano;P. Oliva-Altamirano
DOI：
10.1086/511749
发表时间：
2006-12
期刊：
The Astrophysical Journal
影响因子：
--
作者：
N. Lehner;B. Savage;P. Richter;K. Sembach;T. Tripp;B. P. W. U. O. N. Dame;U. Wisconsin;U. Bonn;Space Telescope Science Institute;U. O. Massachusetts
通讯作者：
N. Lehner;B. Savage;P. Richter;K. Sembach;T. Tripp;B. P. W. U. O. N. Dame;U. Wisconsin;U. Bonn;Space Telescope Science Institute;U. O. Massachusetts