即使是中心星系也会受到其环境的影响：冷气体吸积的宇宙虹吸效应
Even central galaxies feel their environment: cosmic siphoning of cool gas accretion
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中文总结 AI 辅助
研究星系中冷气体吸积关键过程，发现孤立中心星系受外部影响显著，存在宇宙虹吸效应，包括晕际竞争吸积和次晕尺度卫星气体被中心星系虹吸，此多尺度机制驱动不同星系冷气体分数差异，体现“富者愈富”范式。
中文摘要 AI 辅助
确定调节星系中冷气体吸积的关键过程对于理解星系生态系统中的重子循环至关重要。近期研究表明，最基本的内部过程可能是晕和中心黑洞之间的竞争，这通过黑洞质量增加与冷气体分数降低之间的普遍关系揭示出来。本文进一步探讨了对中心星系冷气体吸积的主要外部影响。发现显著偏离μHI - MBH关系的星系绝大多数是没有大量卫星的孤立中心星系。这些孤立、贫气的中心星系表现出系统地更高的黑洞与恒星质量比和更突出的心核，表明对AGN反馈更敏感。在更大尺度上，它们优先位于大质量邻近晕附近。将这些解释为“宇宙虹吸”的证据，这是一个多尺度、引力驱动的过程，其中冷气体被引导到更深的势阱中。在晕际尺度上，表现为竞争吸积；在次晕尺度上，类似的虹吸作用在星系群和星系团内起作用。这种多尺度机制自然地驱动了孤立星系和星系群中心之间，或孤立星系中有无大质量邻近晕的星系之间冷气体分数的差异，体现了宇宙“富者愈富”的范式。
英文摘要
Identifying the key processes regulating cool gas accretion in galaxies is essential for understanding the baryon cycle within galactic ecosystems. Recent studies indicate that the most fundamental internal process is likely the competition between halos and central black holes. This is revealed through a universal relation between increasing black hole masses and decreasing cool gas fraction ($μ_{\rm HI} \equiv M_{\rm HI}/M_{\star} \propto M_{\rm BH}^{-0.6}$). Here we further explore the primary external effects on cool gas accretion in central galaxies. We find that galaxies deviating significantly from the $μ_{\rm HI}-M_{\rm BH}$ relation are overwhelmingly isolated central galaxies without substantial satellites. These isolated, gas-poor centrals exhibit systematically higher black-hole-to-stellar-mass ratios and more prominent bulges, suggesting a greater susceptibility to AGN feedback. At larger scales, they are preferentially located near massive neighboring halos. We interpret these as evidence of "cosmic siphoning'' -- a multi-scale, gravity-driven process in which cool gas is channeled into deeper potential wells. On inter-halo scales, it manifests as competitive accretion: massive dark matter halos intercept cold filamentary streams, starving neighboring low-mass halos and quenching their star formation. On sub-halo scales, an analogous siphoning operates within groups and clusters, where the central galaxy systematically drains gas from its satellites through tidal interactions and accretion of satellite circumgalactic medium. This multi-scale mechanism -- from inter-halo competition to central-satellite interplay -- naturally drives the observed differences in the cool gas fractions between isolated and group centrals, or among the isolated, between those with and without a massive neighboring halo, and embodies a cosmic "rich-get-richer" paradigm.
