The Bimodal Absorption System Imaging Campaign (BASIC). I. A Dual Population of Low-metallicity Absorbers at z < 1
The Bimodal Absorption System Imaging Campaign (BASIC). I. A Dual Population of Low-metallicity Absorbers at z < 1
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DOI：
10.3847/1538-4357/acb047
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发表时间：
2022-04
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通讯作者：
M. A. Berg;N. Lehner;J. Howk;J. O’Meara;J. Schaye;L. Straka;K. Cooksey;T. Tripp;J. Prochaska;B. Oppenheimer;S. Johnson;S. Muzahid;R. Bordoloi;J. Werk;A. Fox;N. Katz;M. Wendt;M. Peeples;J. Ribaudo;J. Tumlinson
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作者：
M. A. Berg;N. Lehner;J. Howk;J. O’Meara;J. Schaye;L. Straka;K. Cooksey;T. Tripp;J. Prochaska;B. Oppenheimer;S. Johnson;S. Muzahid;R. Bordoloi;J. Werk;A. Fox;N. Katz;M. Wendt;M. Peeples;J. Ribaudo;J. Tumlinson
双峰吸收系统成像运动(BASIC)的目标是描述在z≲1的23个类星体场中36个H i选择的部分莱曼极限系统(PLLSS)和莱曼极限系统(LLSS)的星系环境。这些pLLSS/LLSS提供了一个独特的具有无偏和良好约束的金属丰度的吸收体样本，使我们能够在z9.0探索富金属和低金属丰度的环星系介质(CGM)的起源，而低金属丰度的pLLSS/LLSS被发现在更多的位置，一个群体出现在星系的CGM中，另一个群体更广泛地分布在宇宙的超稠密区域。使用与星系无关的吸收体，我们估计星际介质的未加权几何平均金属丰度在z<；1时为[X/H]≲−2.1，低于先前的估计。
The bimodal absorption system imaging campaign (BASIC) aims to characterize the galaxy environments of a sample of 36 H i-selected partial Lyman limit systems (pLLSs) and Lyman limit systems (LLSs) in 23 QSO fields at z ≲ 1. These pLLSs/LLSs provide a unique sample of absorbers with unbiased and well-constrained metallicities, allowing us to explore the origins of metal-rich and low-metallicity circumgalactic medium (CGM) at z 9.0 , whereas low-metallicity pLLSs/LLSs are found in more diverse locations, with one population arising in the CGM of galaxies and another more broadly distributed in overdense regions of the universe. Using absorbers not associated with galaxies, we estimate the unweighted geometric mean metallicity of the intergalactic medium to be [X/H] ≲ −2.1 at z < 1, which is lower than previously estimated.