论文标题
间歇性AGN发作驱动流出，并以大量可观察的负载因子传播
Intermittent AGN episodes drive outflows with a large spread of observable loading factors
论文作者
论文摘要
大规模银河流出的特性（例如它们的动能和动量速率）与活性银河核（AGN）的光度相关。这是通过风向流出模型很好地解释的，其中AGN光度的一部分驱动流出。但是，在许多星系中观察到了与这些相关性的显着偏离。这可能会发生这种情况，因为AGN光度在时间尺度较短（$ \ sim 10^4-10^5 $ yr）上的变化（$ \ sim 10^6 $〜yr）。我们使用1D数值模拟研究了AGN光度变化对流出性能的影响。这种效果可以解释PDS 456中非常弱的流出量：如果其核目前比长期平均亮度明亮得多，则流出没有时间对这种发光度变化反应。相反，MRK 231中的流出与几乎连续的AGN驱动相一致，而IRAS F11119+3257代表两者之间的中间情况。考虑到AGN的种群，我们发现非常低的动量载荷因子$ \ dot {p} _ {\ rm out} <l _ {\ rm agn}/c $在很大一部分的物体中应看到 - 根据AGN可变性和Galaxy Gasny Gase fraction的特性，最高为$ 15 \％$ $。负载因子的预测分布与可用的观察数据一致。我们讨论该模型如何有助于限制流出通胀期间AGN的占空比周期，对多相和空间上不同的外流的影响，并提出改善数值模拟中AGN处方的方法。
The properties of large-scale galactic outflows, such as their kinetic energy and momentum rates, correlate with the luminosity of the active galactic nucleus (AGN). This is well explained by the wind-driven outflow model, where a fraction of the AGN luminosity drives the outflow. However, significant departures from these correlations have been observed in a number of galaxies. This may happen because AGN luminosity varies on a much shorter timescale ($\sim 10^4-10^5$~yr) than outflow properties do ($\sim 10^6$~yr). We investigate the effect of AGN luminosity variations on outflow properties using 1D numerical simulations. This effect can explain the very weak outflow in PDS 456: if its nucleus is currently much brighter than the long-term average luminosity, the outflow has not had time to react to this luminosity change. Conversely, the outflow in Mrk 231 is consistent with being driven by an almost continuous AGN, while IRAS F11119+3257 represents an intermediate case between the two. Considering a population of AGN, we find that very low momentum loading factors $\dot{p}_{\rm out} < L_{\rm AGN}/c$ should be seen in a significant fraction of objects - up to $15\%$ depending on the properties of AGN variability and galaxy gas fraction. The predicted distribution of loading factors is consistent with the available observational data. We discuss how this model might help constrain the duty cycles of AGN during the period of outflow inflation, implications for multiphase and spatially distinct outflows, and suggest ways of improving AGN prescriptions in numerical simulations.
