AI 中文总结
本研究通过MACER框架的流体动力学模拟，解释低红移PG类星体宿主星系气体占比高且与AGN光度关联弱的现象，证实其符合长期抛射式AGN反馈的物理机制。
AI 中文摘要
我们利用MACER框架下的高分辨率流体动力学模拟，解释为何低红移PG类星体宿主星系能保留大量冷气体库，其气体占比与气尘质量比对瞬时AGN光度几乎无依赖。本文是系列研究的第三篇，该系列研究受宇宙气体流入影响的盘星系中AGN反馈。模拟包含多相气体、恒星形成、恒星反馈，以及自洽的辐射与机械AGN反馈。我们再现了观测到的宿主星系气体含量与AGN光度的弱关联，光度范围为L_AGN/L_Edd ~ 10^{-5}-10，而星系仍会经历显著的气体耗尽与恒星形成淬灭。在淬灭阶段，冷气体质量下降近三个数量级，气体分布演化显示AGN反馈逐步从星系中移除冷、热气体。恒星形成率与冷气体质量的关联比与AGN光度更紧密。该行为源于时标不匹配：AGN光度变化时标约为10^5-10^6年，而AGN驱动的重复外流会在约10亿年的时间尺度上累积耗尽星系级气体库。因此，我们的模拟为富含气体的PG类星体宿主星系提供了物理解释，并表明其观测到的气体性质与有效、长期的抛射式AGN反馈完全一致。
英文摘要
We use high-resolution hydrodynamic simulations in the MACER framework to explain why low-redshift PG quasar hosts can retain substantial cold-gas reservoirs, with gas fractions and gas-to-stellar mass ratios showing little dependence on instantaneous AGN luminosity. This paper is the third in a series systematically studying AGN feedback in a disk galaxy subject to cosmological gas inflow. The simulations include multiphase gas, star formation, stellar feedback, and self-consistent radiative and mechanical AGN feedback. We reproduce the observed weak connection between host-galaxy gas content and AGN luminosity over L_AGN/L_Edd ~ 10^{-5}-10, while the galaxy nevertheless undergoes pronounced gas depletion and star-formation quenching. During the quenching phase, the cold-gas mass declines by nearly three orders of magnitude, and the evolution of the gas distribution shows that AGN feedback progressively removes both cold and hot gas from the galaxy. The star formation rate is more closely linked to the cold-gas mass than to AGN luminosity. This behavior arises from a timescale mismatch: AGN luminosity varies on ~ 10^5-10^6 yr timescales, whereas repeated AGN-driven outflows cumulatively deplete the galaxy-scale gas reservoir over ~ 1 Gyr. Our simulations therefore provide a physical explanation for the gas-rich PG quasar hosts and show that their observed gas properties are fully consistent with effective, long-term ejective AGN feedback.
Comments14 pages, 9 figures. To be submitted to ApJ
