NGC 4051中电离吸收体的时间演化诊断。II. 高通量时间分辨光谱学
Time-evolving Diagnostic of the Ionized Absorbers in NGC 4051. II. High-throughput Time-resolved Spectroscopy
AI总结：
研究AGN NGC 4051电离吸收体，利用XMM - Newton和NuSTAR联合观测进行时间分辨光谱学研究，通过TEPID建模打破密度 - 距离简并，确定吸收体相关参数，得出总能量外流率低、对宿主星系无显著机械影响的结论。
AI中文摘要：
活动星系核（AGNs）是宇宙中最强大的能量源之一。吸积释放的能量会强烈影响周围环境，直至宿主星系及更远。尽管核外流普遍存在，但由于其数密度\(n_e\)和径向位置\(r\)之间的简并性，在用于拟合观测的光电离平衡模型中，核外流的特征描述很差。这种简并性阻碍了对气体能量学以及AGN能量向外传输效率的自洽确定。我们分析了对明亮且高度可变的AGN NGC 4051的XMM - Newton和NuSTAR联合观测。高通量使得能够进行时间分辨光谱学研究，从而研究其三个主要电离吸收体的演化。由于气体电离变化的时间尺度取决于其数密度，对其进行约束可以打破密度 - 距离简并。我们使用时间演化光电离装置（TEPID）对外流的时间演化进行建模。我们将观测分为37个时间分辨光谱，每个光谱持续几千秒（总时长160千秒），并将它们与时间分辨电离光谱联合拟合。对于不透明度最高且电离程度中等的吸收体，我们完全约束了\(n_e = 10^7 cm^{-3}\)和\(r = 10^4\)引力半径。这个距离与光学和紫外宽线区域以及软X射线发射线的距离相同。最快且电离程度最高的吸收体位于\(r < 600 r_G\)，与Fe K\(\alpha\)线的宽成分共空间。最慢且电离程度最低的吸收体位于\(r \geq 3.8 \cdot 10^5 r_G\)，与冷盘和窄Fe K\(\alpha\)的距离相同。总能量外流率低于\(10^{-4} L_{bol}\)，排除了对宿主星系有显著机械影响的可能性。
英文摘要：
Active Galactic Nuclei (AGNs) are one of the most powerful sources in the Universe. The accretion-liberated energy can strongly impact the surrounding environment, up to the host galaxy and beyond. Notwithstanding their ubiquitous presence, nuclear outflows are poorly characterised, mainly due to the degeneracy between their number density $n_e$ and radial location $r$, intrinsic in the photoionisation equilibrium models which are usually employed to fit the observations. This degeneracy prevents a self-consistent determination of the gas energetics and, therefore, of the efficiency in transporting the AGN energy outwards. We analyse a joint XMM-Newton and NuSTAR observation of the bright, highly-variable AGN NGC 4051. The high flux allows to perform time-resolved spectroscopy and, thus, to study the evolution of its three main ionised absorbers. Since the timescale of the gas ionisation variability depends on its number density, constraining it allows to break the density-distance degeneracy. We employ the Time-Evolving PhotoIonisation Device (TEPID) to model the temporal evolution of the outflows. We split the observation in 37 time-resolved spectra, each few kiloseconds long (total duration 160 ksec), and we fit them jointly with the time-resolved ionised spectra. We fully constrain $n_e=10^7 cm^{-3}$ and $r=10^4$ gravitational radii for the absorber with the highest opacity and intermediate ionisation. This distance is the same of the optical and UV Broad Line Region and of the soft X-ray emission lines. The fastest and most ionised absorber is at $r<600 r_G$, cospatial with the broad component of the Fe K$α$ line. The slowest and least ionised absorber is at $r \geq 3.8 \cdot 10^5 r_G$, the same distance of the cold torus and the narrow Fe K$α$. The total energy outflow rate is below $10^{-4} L_{bol}$, ruling out a meaningful mechanical impact on the host galaxy.
