发表机构
University of California, Los Angeles; Carnegie Observatories; California Institute of Technology; Department of Physics, University of Notre Dame; Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), Northwestern University（加州大学洛杉矶分校; 卡内基天文台; 加州理工学院; 圣母大学物理系; 西北大学天体物理学跨学科探索与研究中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过凯克巡天分析两个低质量$z\sim2.3$星系的内部CGM，发现其吸收特征与典型星系一致，热特性相似，但运动学复杂性和不受束缚气体比例随恒星质量变化。
AI 中文摘要
我们展示了凯克重子结构巡天（KBSS）扩展项目的结果，该项目聚焦于$z\sim2.3$处类星体视线发射星系（InCLOSE）的内部环星系介质（CGM）。我们分析了两个低质量星系$\log{(\rm{M_*} / \rm{M_\odot})} \leq 9$，它们位于类星体的小投影距离内$D_{\rm tran} \leq 50~{\rm kpc}$（$D_{\rm tran} /R_{\rm vir} \leq 0.75$）。其中一个星系被凯克/KCWI探测为明亮的莱曼α发射体（通过后续凯克/MOSFIRE光谱确认），另一个则是凯克/MOSFIRE偶然发现的线发射体。两个星系的星云和形态特性都与典型的低质量$z\sim2.3$恒星形成星系一致。通过背景类星体的凯克/HIRES光谱分析其CGM吸收，未探测到低电离金属吸收（低电离离子；如Si II），普遍探测到中间电离离子（如C IV）和高电离离子（O VI），运动学上复杂的吸收（每个星系晕中≥7个分量）分布在$|\Delta v|\pm 150~{\rm km~s^{-1}}$范围内，且两个星系晕中均未探测到明确不受束缚的气体。我们分析了部分CGM分量的热特性，发现大多数（6/10）分量的温度与银河系紫外背景加热一致（$\log{(T/\rm{K})_{\mathrm{med}}}=4.0$），而其余分量则拥有短寿命的中间温度气体，需要额外加热或快速补充（$4.6 \leq \log{(T/\rm{K})} \leq 5.1$），这些吸收体的内能由热展宽主导，其内部（湍流）速度均为亚音速，而它们在晕中的运动可能为超音速。这些结果暗示$z\sim2.3$的CGM在运动学复杂性和不受束缚气体比例方面随恒星质量变化，而热特性保持相似。
英文摘要
We present results from an extension to the Keck Baryonic Structure Survey (KBSS) that focuses on the Inner Circumgalactic Medium (CGM) of QSO Line Of Sight Emitting galaxies at z$\sim$2.3 (InCLOSE). We analyze two low-mass galaxies $\log{(\rm{M_*} / \rm{M_\odot})} \leq 9$ that are within small a projected distance of a QSO $D_{\rm tran} \leq 50~{\rm kpc}$ ($D_{\rm tran} /R_{\rm vir} \leq 0.75$). One galaxy is detected as a bright Lyman- Emitter with Keck/KCWI (confirmed with follow-up Keck/MOSFIRE spectra), and the other as a serendipitous line emitter with Keck/MOSFIRE. Both galaxies have nebular and morphological properties consistent with those of typical low-mass z$\sim$2.3 star-forming galaxies. Analysis of their CGM absorption as seen with Keck/HIRES spectra of the background QSOs shows no detections of low-ionization metal absorption (low-ions; e.g., Si II), ubiquitous detections of intermediate- (e.g., C IV) and high-ions (O VI), kinematically complex absorption ($\geq$7 components per galaxy halo) spread over $|Δv|\pm 150~{\rm km~s^{-1}}$, and no unambiguously unbound gas is detected in either galaxy halo. We analyze the thermal properties of a subset of CGM components, finding that the majority (6/10) have temperatures consistent with heating from the metagalactic UV background ($\log{(T/\rm{K})_{\mathrm{med}}}=4.0$) while the remainder possess short-lived, intermediate temperature gas that would require additional heating or rapid replenishment ($4.6 \leq \log{(T/\rm{K})} \leq 5.1$), the internal energy of these absorbers are dominated by thermal broadening, their internal (turbulent) velocities are all subsonic, while their motions through the halo are likely supersonic. These results hint that the z2.3 CGM changes with stellar mass in terms of kinematic complexity and unbound gas fraction, while thermal properties remain similar.
Comments31 pages, 14 figures, resubmitted to ApJ reviewer with minor revisions
