AI 中文总结
本研究通过30个高分辨率宇宙学zoom-in模拟，发现再循环气体主导超大质量黑洞的吸积总量，为黑洞富金属燃料的起源提供了宇宙学星系演化与恒星再循环层面的解释。
AI 中文摘要
理解超大质量黑洞（SMBH）吸积气体的起源与化学性质，是将黑洞增长与星系演化关联起来的关键。本研究利用一套30个高分辨率宇宙学zoom-in模拟，探究z=0时恒星质量为10^10.9-11.9 M⊙、黑洞质量为10^8.5-9.7 M⊙的大质量星系中，吸积到SMBH的气体的化学性质。通过追踪单个气体粒子的完整宇宙学历史，确定其起源与增丰途径。吸积气体分为四类：主晕早期形成阶段吸积的“早期”气体、源自其他星系或子晕的“外部”气体、经主星系内恒星演化过程（包括渐近巨星分支（AGB）星风与超新星抛射物）增丰的“再循环”气体，以及从星系际介质吸积的“平滑”气体。研究发现，再循环气体在吸积总量中占主导，且在早期就已富金属；其他起源的气体在被黑洞吸积前，通常会在星系环境中经历渐进式化学增丰。平均丰度比显示出极弱的红移演化，与类星体宽线区推断的高金属量大致相符。研究结果表明，供给SMBH的富金属气体，是宇宙学星系演化与恒星再循环的自然产物。
英文摘要
Understanding the origin and chemical properties of gas accreted by supermassive black holes (SMBHs) is essential for linking black hole growth to galaxy evolution. Using a suite of 30 high-resolution cosmological zoom-in simulations, we investigate the chemical properties of gas accreted onto SMBHs in massive galaxies with stellar masses of $10^{10.9-11.9}\,\rm M_\odot$ and black hole masses of $10^{8.5-9.7}\,\rm M_\odot$ at $z=0$. By tracing the full cosmological histories of individual gas particles, we identify their origins and enrichment pathways. The accreted gas is classified into four categories: ``early'' gas accreted during the early assembly phase of the main halo, ``external'' gas originating from other galaxies or subhalos, ``recycled'' gas enriched through stellar evolution processes within the primary galaxy, including asymptotic giant branch (AGB) winds and supernova ejecta, and ``smooth'' gas accreted from the intergalactic medium. We find that recycled gas dominates the accretion budget and is already metal rich at early epochs. Gas from other origins typically undergoes gradual chemical enrichment within the galactic environment prior to black hole accretion. The mean abundance ratios show only weak redshift evolution and are broadly compatible with the high metallicities inferred for quasar broad-line regions. Our results suggest that metal-rich gas supply to SMBHs arises naturally from cosmological galaxy evolution and stellar recycling.
Comments14 pages, 1 table, 4 figures
