AI 中文总结
该研究利用XRISM对NGC 4151的14次观测，揭示其外流具有全局有序局部复杂的结构，低速暖吸收体始终存在，极高速和超高速外流在耀斑后10 ks及低流量时最强，高速流为磁驱动且受辐射压力影响。
AI 中文摘要
X射线观测可探测活动星系核（AGN）内的吸积流，揭示出最高的气体柱密度和最快的外流。XRISM搭载的Resolve量热计光谱仪在近邻的赛弗特1型AGN NGC 4151中发现了迄今为止最多样化的外流，该源可能属于“外观变化源”（CLAGN）。本文报告了对NGC 4151进行的14次XRISM观测中的外流变化情况，这些观测总曝光量达0.9 Ms，观测周期为395天。我们研究了关键外流参数对硬度和强度选择的依赖性，以及相对于耀斑和下降事件的时间函数关系。结果表明，外流结构具有全局有序但局部复杂的特征。低速“暖吸收体”（WA）成分始终被观测到，其外流速度v_out约为100-1000 km/s，可能代表在10^4 - 10^5 GM/c²半径处的失败外流，位于环面的内边界。相比之下，“极高速”外流（VFO）和“超高速”外流（UFO）的外流速度v_out约为10^3-10^4 km/s、0.033-0.33 c，在耀斑峰值后10 ks及低流量时期强度最高。10 ks是AGN中报道的最短耀斑-外流响应时标之一，表明观测到的外流靠近驱动位点。吸收度量分布（AMD）和大外流动量率表明，铁K波段可见的高速流是磁驱动的，同时具有局部团块状特征，可能由辐射压力导致；耀斑后这两种机制中的一种或两种都会增强，且在低流量窗口中最为明显。
英文摘要
X-ray observations probe the inner accretion flow within active galactic nuclei, revealing the highest gas column densities and fastest winds. The most diverse winds yet revealed with the Resolve calorimeter spectrometer aboard XRISM are found in NGC~4151, a nearby Seyfert-1 AGN that may qualify as a ``changing-look'' source (CLAGN). Herein, we report on wind variability in 14 XRISM observations of NGC~4151, summing to 0.9~Ms of exposure over a period of 395 days. We examined the dependence of key wind parameters on hardness and intensity selections, and as a function of time relative to flaring and dip events. The results suggest a globally organized but locally complex wind structure. Slow ``warm absorber'' components (WAs; $v_{\rm{out}} \sim 100-1000~\rm{km~s^{-1}}$) are always observed and likely represent failed winds at radius of $10^4 - 10^5 GM/c^2$, within the inner wall of the torus. In contrast, ``very fast'' and ``ultra-fast'' outflows (VFOs and UFOs; $v_{\rm{out}} \sim 10^3-10^4~\rm{km~s^{-1}}$, $v_{\rm{out}} \sim 0.033-0.33~c$) are strongest 10~ks after the peak of flares, and during periods with low flux. Ten kiloseconds is among the shortest flare--wind response timescales reported in an AGN, suggesting that the winds are observed close to the launching site. The absorption measure distribution (AMD) and the large outflow momentum rates suggest that the high-velocity flows visible in the Fe~K band are magnetically driven, while locally clumpy, likely owing to radiation pressure; one or both of these mechanisms may be enhanced following a flare and most visible during low-flux windows.
CommentsAccepted for publication in ApJ
