AI 中文总结
该研究利用FAST巡天和DESI光谱目录，对36个星系团进行叠加研究，采用光谱叠加技术探测星系HI质量等，发现星系团环境使HI质量和比值下降，即使在5R200处仍低于场星系，强调了扩展环境对星系冷气体库及抑制星系的关键作用。
AI 中文摘要
我们利用FAST全天氢元素中性原子（HI）巡天（FASHI）和主要来自暗能量光谱仪（DESI）的大量光谱目录，对36个红移z<0.07的本地星系团及其周围的HI含量进行了叠加研究。我们采用光谱叠加技术来探测成员星系的平均HI质量和HI与恒星质量比（$M_{\rm HI}/M_*$），恒星质量低至$M_*\sim 10^9M_\odot$，投影中心距离跨度至5R200。分析揭示了显著的环境效应：$M_{\rm HI}$和$M_{\rm HI}/M_*$均朝着星系团中心稳步下降，从外围到核心平均下降约0.5个量级。关键的是，我们发现即使在5R200处，星系的$M_{\rm HI}/M_*$仍低于场星系。这为星系团外围大量的气体剥离和预处理提供了直接的统计证据，可能发生在正在落入的星系群和大规模丝状结构中。通过按g - r颜色进一步划分样本，我们表明在固定星系颜色下HI缺乏持续存在：即使是最蓝的星系团成员，其$M_{\rm HI}/M_*$也比类似颜色的场星系低约0.5个量级，反映了在完全光学转变之前环境对冷气体库的影响。星系团及其外围的总HI质量与宇宙学模拟的预测大致相符。我们的结果强调了扩展的星系团环境在通过在星系进入密集星系团核心之前耗尽其冷气体库来抑制星系方面的关键作用。
英文摘要
We present a stacking study of the neutral atomic hydrogen (HI) content in and around 36 local galaxy clusters at $z<0.07$, using a combination of the FAST all sky HI survey (FASHI) and the extensive spectroscopic catalog mainly from the Dark Energy Spectroscopic Instrument (DESI). We employ spectral stacking techniques to probe the average HI mass and HI-to-stellar mass ratio ($M_{\rm HI}/M_*$) for member galaxies down to stellar masses of $M_*\sim 10^9M_\odot$, spanning a projected cluster-centric distance to $5R_{200}$. Our analysis reveals a pronounced environmental effect: both $M_{\rm HI}$ and $M_{\rm HI}/M_*$ decrease steadily towards the cluster center, dropping by $\sim 0.5$ dex on average from the outskirts to the core. Crucially, we find that $M_{\rm HI}/M_*$ of galaxies remain lower than the field galaxies even at the $5R_{200}$. This provides direct, statistical evidence for substantial gas stripping and pre-processing in the cluster outskirts, likely occurring in infalling groups and large-scale filaments. By further splitting the sample by $g-r$ color, we show that the HI deficiency persists at fixed galaxy color: even the bluest cluster members exhibit $\sim 0.5$~dex lower $M_{\rm HI}/M_*$ than field galaxies of similar color, reflecting environmental effects on the cold gas reservoir prior to full optical transformation. The total HI mass within clusters and their outskirts agrees broadly with predictions from cosmological simulation. Our results underscore the critical role of the extended cluster environment in quenching galaxies by depleting their cold gas reservoirs well before they enter the dense cluster core.
Comments32 pages, 15 figures, ApJ accepted
