从FAST全天HI巡天DR2中识别出的459个星系群样本
A Sample of 459 Galaxy Groups Identified from the FAST All Sky HI Survey DR2
- National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）
- CAS Key Laboratory of FAST, NAOC, Chinese Academy of Sciences（中国科学院FAST国家重点实验室，国家天文台，中国科学院）
- School of Astronomy, University of Chinese Academy of Sciences（中国科学院大学天文学系）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
基于FASHI DR2直接识别出459个星系群，发现总HI质量与恒星质量正相关且比值随质量下降，为研究星系演化提供样本。
AI中文摘要：
富含HI的星系群是理解星系演化和环境效应的关键实验室，构建此类星系群的样本对于相关研究至关重要。利用FAST全天HI巡天（FASHI）数据发布第二版（DR2），这是目前可用最大且最深的HI星表，我们直接基于HI信号识别星系群，无需依赖光学预选。采用具有密度对比准则且最少成员数为五的群查找算法，我们得到了包含3015个HI源的459个星系群的星表。利用档案光谱数据，我们识别光学对应体，并推导成员星系的总恒星质量，作为星系群总质量的代理。星系群的红移分布峰值在z~0.02处，总HI质量峰值在约10^{10}太阳质量处。我们发现总HI质量与总恒星质量之间存在显著正相关，与先前叠加研究中报道的HI质量随暗晕质量增加而增加的结果一致。总HI质量与总恒星质量的比值随总恒星质量的增加而显著下降，表明星系群中HI逐渐耗竭。我们的样本为未来研究本地宇宙中的星系演化和大规模结构提供了丰富目标。
英文摘要：
Groups of HI-rich galaxies are key laboratories for understanding galaxy evolution and environmental effects, constructing samples of such groups is fundamental for relevant studies. Using the FAST All Sky HI Survey (FASHI) Data Release 2 (DR2), currently the largest and deepest HI catalog available, we identify galaxy groups directly from HI signals, without relying on optical pre-selection. A group-finding algorithm with a density contrast criterion and a minimum membership of five yields a catalog of 459 galaxy groups containing 3015 HI sources. Using archival spectroscopic data, we identify optical counterparts and derive total stellar masses of member galaxies as a proxy for the group total mass. The group redshift distribution peaks at z ~ 0.02, and the total HI mass peaks at ~ 10^{10} M_{\odot}. We find a significant positive correlation between total HI mass and total stellar mass, consistent with the increase in HI mass with halo mass reported in previous stacking studies. The ratio of total HI mass to total stellar mass decreases significantly with increasing total stellar mass, indicating gradual HI depletion in groups. Our sample provides rich targets for future studies of galaxy evolution and large-scale structure in the local Universe.
