AI 中文总结
研究了红移\(z\approx0.55\)时大质量BCG周围冷气体情况，利用暗能量光谱仪观测数据，将BCG与场星系对比，追踪径向分布，发现其有双重环境特征，为暗物质晕环境处理理论模型提供观测约束。
AI 中文摘要
星系团是极端的宇宙实验室，环境过程极大地重塑了其星系组成部分，但其对中心星系气态晕的影响仍知之甚少。本文展示了在红移\(z\approx0.55\)时，对大质量最亮星系团星系（BCG）周围冷气体的首次统计映射。利用暗能量光谱仪观测的超过百万个背景类星体的叠加视线光谱中的镁II吸收，将BCG与匹配的场星系样本进行比较，并追踪从40千秒差距到15百万秒差距的径向分布。分析揭示了显著的双重环境特征：在200千秒差距内，BCG周围的星系际介质（CGM）与场星系相比受到显著抑制，而在较大半径（200千秒差距到10百万秒差距）出现明显的冷气体过剩。这种从核心抑制到大规模增强的清晰转变描绘了一种由致密环境调节气体的新观测模式。这表明星系团不仅可能在核心剥离气体，还可能促进其在郊区的积累。我们的结果为最大质量暗物质晕及其周围环境处理的理论模型提供了关键观测约束。
英文摘要
Galaxy clusters represent extreme cosmic laboratories where environmental processes dramatically reshape their constituent galaxies, yet their effect on the gaseous halos of central galaxies remains poorly constrained. Here we present the first statistical mapping of cool gas around massive brightest cluster galaxies (BCGs) at $z\approx0.55$. Using Mg II absorption in stacked sight-line spectra from over a million background quasars observed by the Dark Energy Spectroscopic Instrument, we compare BCGs to a matched sample of field galaxies and trace the radial profile from 40 kpc to 15 Mpc. Our analysis reveals a striking dual environmental signature: within 200 kpc, the circumgalactic medium (CGM) around BCGs is significantly suppressed compared to that of field galaxies, while at larger radii (200 kpc to 10 Mpc) a pronounced excess of cool gas emerges. This clear transition from suppression in the core to enhancement on such large scales delineates a novel observed pattern for gas regulation by the dense environment. It suggests that clusters may not only strip gas in the core but also facilitate its accumulation in the outskirts. Our results provide key observational constraints on theoretical models of environmental processing in and around the most massive dark matter halos.
