xGASS：小星系群中富含气体的中央星系及其与宇宙网气体供给的联系
xGASS: Gas-rich central galaxies in small groups and their connections to cosmic web gas feeding
摘要：
我们使用深HI观测获得的扩展GALEX Arecibo SDSS调查（xGASS）的一部分，研究跨环境的中央星系的冷气体特性。我们发现，在10^10.2 Msun以下的恒星质量下，成组的中央星系的平均原子氢气分数比相同恒星质量的孤立星系高约0.3dex。在这样的恒星质量下，星系群中央星系通常是以N=2的小星系群出现。这些低质量星系团中央星系中较高的HI含量反映了它们较高的平均恒星形成活动和分子氢含量。在较大的恒星质量下，这种差异消失了，与孤立的星系相比，成组的中央星系具有相似（甚至更小）的气体储存和恒星形成活动。我们讨论了能够解释我们的研究结果的可能方案，并建议低质量群中央星系中较高的气体含量可能是由于宇宙网或HI丰富的小型合并的贡献，这也助长了它们增强的恒星形成活动。
英文摘要：
We use deep HI observations obtained as part of the extended GALEX Arecibo SDSS survey (xGASS) to study the cold gas properties of central galaxies across environments. We find that, below stellar masses of 10^10.2 Msun, central galaxies in groups have an average atomic hydrogen gas fraction ~0.3dex higher than those in isolation at the same stellar mass. At these stellar masses, group central galaxies are usually found in small groups of N=2 members. The higher HI content in these low mass group central galaxies is mirrored by their higher average star formation activity and molecular hydrogen content. At larger stellar masses, this difference disappears and central galaxies in groups have similar (or even smaller) gas reservoirs and star formation activity compared to those in isolation. We discuss possible scenarios able to explain our findings and suggest that the higher gas content in low mass group central galaxies is likely due to contributions from the cosmic web or HI-rich minor mergers, which also fuel their enhanced star formation activity.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
