论文标题
双峰吸收系统成像运动（基本）I。Z $ <1 $的低金属吸收器的双重人群
The Bimodal Absorption System Imaging Campaign (BASIC) I. A Dual Population of Low-metallicity Absorbers at z $<1$
论文作者
论文摘要
双峰吸收系统成像运动（基本）旨在表征23个QSO字段中36个Hi选择的部分Lyman限制系统（PLLSS）和Lyman Limit Systems（LLSS）样本的星系环境，该QSO领域的$ z \ simssim 1 $。这些PLLS/LLSS提供了独特的吸收剂样本，具有无偏见且受良好约束的金属性，使我们能够探索$ z <1 $的金属富含金属富含金属和低金属的环境培养基（CGM）的起源。在这里，我们介绍了这些QSO田地（19个PLLSS）中的11个凯克/KCWI和VLT/MUSE观察，它们与HST/ACS成像相结合，以识别和表征与吸收器相关的星系。我们发现了23个独特的吸收器相关星系，每个吸收剂平均有一个相关的星系。对于七个吸收器，所有$ <10 \％$ $太阳金属都没有发现与$ \ log m_ \ star \ gtrsim 9.0 $之间的相关星系，$ρ/r_ {vir} $和$ |ΔV|/v_/v_/v_/v_/v_ {enc} \ le $ 1.5 $ $ $ $ $ $ 1.5相对于吸收率。 We do not find any strong correlations between the metallicities or HI column densities of the gas and most of the galaxy properties, except for the stellar mass of the galaxies: the low-metallicity ([X/H] $\le -1.4$) systems have a probability of $0.39^{+0.16}_{-0.15}$ for having a host galaxy with $\log M_\star \ ge 9.0 $在$ρ/r_ {vir} \ le 1.5 $中，而较高的金属吸收器的概率为$ 0.78^{+0.10} _ { - 0.13} $。这意味着$ z <1 $的金属元素/llss通常与带有$ \ log m_ \ star> 9.0 $的星系CGM相关，而低的金属pllss/llss则建立在更多样化的位置，其中一个人群在Galaxies的CGM中产生了一个更广泛的分布，并且是多种多样的分布。使用与星系无关的吸收器，我们估计绘制培养基的未加权几何金属度为[x/h] $ \ lyssim -2.1 $ at $ z <1 $，低于先前估计的。
The bimodal absorption system imaging campaign (BASIC) aims to characterize the galaxy environments of a sample of 36 HI-selected partial Lyman limit systems (pLLSs) and Lyman limit systems (LLSs) in 23 QSO fields at $z \lesssim 1$. 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 $z<1$. Here we present Keck/KCWI and VLT/MUSE observations of 11 of these QSO fields (19 pLLSs) that we combine with HST/ACS imaging to identify and characterize the absorber-associated galaxies. We find 23 unique absorber-associated galaxies, with an average of one associated galaxy per absorber. For seven absorbers, all with $<10\%$ solar metallicities, we find no associated galaxies with $\log M_\star \gtrsim 9.0$ within $ρ/R_{vir}$ and $|Δv|/v_{esc} \le$ 1.5 with respect to the absorber. We do not find any strong correlations between the metallicities or HI column densities of the gas and most of the galaxy properties, except for the stellar mass of the galaxies: the low-metallicity ([X/H] $\le -1.4$) systems have a probability of $0.39^{+0.16}_{-0.15}$ for having a host galaxy with $\log M_\star \ge 9.0$ within $ρ/R_{vir} \le 1.5$, while the higher metallicity absorbers have a probability of $0.78^{+0.10}_{-0.13}$. This implies metal-enriched pLLSs/LLSs at $z<1$ are typically associated with the CGM of galaxies with $\log M_\star > 9.0$, 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] $\lesssim -2.1$ at $z<1$, which is lower than previously estimated.
