QUEST矮星系中的低质量重子循环 I：样本定义与首批结果
The Low-Mass Baryon Cycle in QUEST Dwarf Galaxies I: Sample definition and first results
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中文总结 AI 辅助
该研究推出QUEST矮星系计划，构建含14个低质量矮星系的样本，发现金属吸收径向分布与恒星质量的关联，揭示星系际介质的多相结构，为探究低质量晕星系际介质富集驱动因素提供数据支撑。
中文摘要 AI 辅助
我们推出了QUEST矮星系计划，该计划结合光学光谱、宽带成像以及明亮背景源的FUV吸收光谱，对一个大样本进行连贯分析，将低质量星系的恒星族群、星际介质和星系际介质关联起来。我们展示了首批发布样本的初步结果，该样本包含14个恒星质量$M_\text{star} \leq 10^9 M_\text{\textodot}$、红移$z\roughly0.001-0.017$的星系，每个星系在投影距离$d_\text{proj}\roughly100$千秒差距处至少有一个星系际介质吸收探针。这个代表性样本将本星系群外矮星系在1/3晕半径内的可用探针数量增加了两倍。我们发现，总硅柱密度随投影距离的下降速度远快于\textsc{Hi}，这表明化学富集的冷气体优先集中在内部星系际介质中，而氢的电离分数随半径增加可能加剧了这种对比。考虑到未观测到的更高电离阶段的硅，我们推断，对于恒星质量对数中位数$\text{log} M_\text{star}/M_\text{\textodot}=7.6$和8.6的矮星系，在$0.3 R_\text{vir}$范围内的冷星系际介质中的总金属质量分别为$\text{log} M_Z/M_\text{\textodot}\roughly4.8$和6.5。这些储量分别对应星系生命周期中产生的总金属的约3%和约16%。质量更大的星系还表现出系统上更强的金属吸收，表明投影距离决定了金属吸收的径向下降，而恒星质量设定了星系际介质金属分布的归一化。单个离子呈现多相结构，低电离物种集中在内部晕，高电离物种延伸得更远。完整的QUEST矮星系巡天将提供所需的统计效力，以确定低质量晕中星系际介质富集的主要驱动因素。
英文摘要
We introduce the QUEST Dwarfs program, which connects low-mass galaxies' stellar populations, interstellar medium, and circumgalactic medium in a large and coherently analyzed sample using a combination of optical spectroscopy, broadband imaging, and FUV absorption spectra of bright background sources .We present initial results from the first-release sample, comprising 14 galaxies with stellar mass $M_\mathrm{star} \leq 10^9 M_\odot$ at $z\approx0.001-0.017$, each with at least one CGM absorption probe at projected distances $d_\mathrm{proj}\lesssim 100$ kpc. This representative sample triples the number of available probes within 1/3 of the halo radius of dwarf galaxies outside of the Local Group. We find that the total silicon column density declines much more rapidly with projected distance than \textsc{Hi}, implying that chemically enriched cool gas is preferentially concentrated in the inner CGM, while the increasing ionization fraction of hydrogen with radius likely enhances this contrast. Accounting for unobserved silicon in higher ionization stages, we infer total metal masses of $\log M_Z/M_\odot\approx4.8$ and $6.5$ in the cool CGM within $0.3 R_\mathrm{vir}$ for dwarfs with median $\log M_\mathrm{star}/M_\odot=7.6$ and 8.6, respectively. These reservoirs correspond to $\approx3$% and $\approx16$% of the total metals produced over the galaxies' lifetimes. More massive galaxies also exhibit systematically stronger metal absorption, suggesting that projected distance governs the radial decline of metal absorption while stellar mass sets the normalization of the CGM metal profile. Individual ions reveal a multiphase structure, with low-ionization species concentrated in the inner halo and higher-ionization species extending farther. The full QUEST Dwarfs survey will provide the statistical power needed to isolate the dominant drivers of CGM enrichment in low-mass halos.
