AMBRA模拟中小红点的寿命与性质
The lifetimes and properties of Little Red Dots in the AMBRA simulation
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中文总结 AI 辅助
本研究在AMBRA模拟中识别小红点，发现气体包裹AGN对暗LRD至关重要，LRD寿命约3-300百万年，随质量增加而延长。
中文摘要 AI 辅助
我们在AMBRA宇宙学流体动力学模拟中识别并分析了小红点（LRDs），通过生成红移5至8之间星系和活动星系核（AGN）的模拟观测来实现。我们使用标准AGN发射模型和“气体包裹”模型生成这些模拟观测，发现气体包裹的AGN的存在对于再现暗LRD（F444W星等>26.0）至关重要。我们发现AMBRA中LRD密度在z=5至z=8之间的下降比观测到的更为陡峭，导致AMBRA在z~6以上相对欠产LRD。加入未分辨的AGN变异性后，随红移的下降趋势变得平缓，AMBRA中的LRD红移演化与其他理论数据集大致一致，并更接近观测结果。我们发现AMBRA中的LRD是预先存在的黑洞-星系系统，正在经历LRD阶段，主要根据AGN相对于其宿主星系的亮度进行选择。由于AGN环境的未分辨性质，无法确定这些LRD阶段的确切持续时间，我们利用可用的时间序列数据来限制AMBRA中LRD的寿命。我们发现AMBRA中绝大多数LRD的寿命在约3至约300百万年之间，LRD寿命随黑洞和宿主星系质量的增加而增加。较低质量的LRD更依赖于拥有气体包裹的AGN，且寿命较短（约30百万年）。较高质量的LRD对其AGN环境不太敏感，但需要更紧凑的宿主星系，且寿命较长（约100百万年）。
英文摘要
We identify and analyze the little red dots (LRDs) in the AMBRA cosmological hydrodynamic simulation, by producing mock observations of the galaxies and active galactic nuclei (AGN) between redshifts 5 and 8. We produce these mock observations with both a standard AGN emission model, and a ``gas-enshrouded'' model, and find that the presence of a gas-enshrouded AGN is instrumental to the reproduction of dim LRDs (F444W magnitude $>$ 26.0). We find a steeper decrease in LRD density between $z=5$ and $z=8$ within AMBRA than seen in observations, resulting in a relative underproduction of LRDs beyond $z\sim6$ in AMBRA. With the addition of unresolved AGN variability, the decline with redshift flattens, and the LRD redshift evolution in AMBRA becomes broadly consistent with other theoretical datasets, and closer to that seen in observations. We find that the LRDs in AMBRA are pre-existing black hole--galaxy systems that are undergoing an LRD phase, selected primarily by the brightness of the AGN relative to its host. While the exact duration of these LRD phases is not possible to determine due to the unresolved nature of the AGN environment, we use the available time-series data to place limits on the lifetimes of the LRDs in AMBRA. We find that the vast majority of LRDs in AMBRA have lifetimes between $\sim3$ and $\sim 300$ Myr with LRD lifetime increasing with both black hole and host galaxy mass. The lower mass LRDs are more dependent on housing a gas-enshrouded AGN, and have shorter lifetimes ($\rm \sim30~Myr$). The higher mass LRDs are less sensitive to their AGN environment, but require more compact host galaxies, and have longer lifetimes ($\rm \sim100~Myr$).
发表机构
- Carnegie Mellon University（卡内基梅隆大学）
- University of Virginia（弗吉尼亚大学）
- Virginia Institute for Theoretical Astronomy, University of Virginia（弗吉尼亚大学理论天体物理研究所）
- Department of Physics, University of Florida（佛罗里达大学物理系）
- Department of Physics & Astronomy, University of California, Riverside（加州大学河滨分校物理与天文系）
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