We have conducted an extensive X-ray spectral variability study of a sample of 20 Compton-thin type II galaxies using broad band spectra from XMM-Newton, Chandra, and Suzaku. The aim is to study the variability of the neutral intrinsic X-ray obscuration along the line of sight and investigate the properties and location of the dominant component of the X-ray-obscuring gas. The observations are sensitive to absorption columns of $N_{\rm H} \sim 10^{20.5-24} {\rm cm^{-2}}$ of fully- and partially-covering neutral and/or lowly-ionized gas on timescales spanning days to well over a decade. We detected variability in the column density of the full-covering absorber in 7/20 sources, on timescales of months-years, indicating a component of compact-scale X-ray-obscuring gas lying along the line of sight of each of these objects. Our results imply that torus models incorporating clouds or overdense regions should account for line of sight column densities as low as $\sim$ a few $\times 10^{21}$ cm$^{-2}$. However, 13/20 sources yielded no detection of significant variability in the full-covering obscurer, with upper limits to $ΔN_{\rm H}$ spanning $10^{21-23}$ cm$^{-2}$. The dominant absorbing media in these systems could be distant, such as kpc-scale dusty structures associated with the host galaxy, or a homogeneous medium along the line of sight. Thus, we find that overall, strong variability in full-covering obscurers is not highly prevalent in Compton-thin type IIs, at least for our sample, in contrast to previous results in the literature. Finally, 11/20 sources required a partial-covering, obscuring component in all or some of their observations, consistent with clumpy near-Compton-thick compact-scale gas.
Warm absorbers are found in many AGN and consist of clouds moving at moderate radial velocities, showing complex ionization structures and having moderate to large column densities. Using 1D numerical calculations, we confirm earlier suggestions that the energy released by an AGN pushes the surrounding gas outward in a bubble until this reaches transparency. Typical AGN episode durations of $5\times 10^4$ yr supply enough energy for this, except in very gas-rich and/or very compact galaxies, such as those in the early Universe. In those galaxies, the AGN might remain hidden for many periods of…
On the equivalent width of the Fe K$α$ line produced by a dusty absorber in active galactic nuclei
被遮蔽的活动星系核提供了一个研究围绕中心引擎的物质的机会。吸收体上的几何和物理约束可以从再处理的活动星系核辐射中推导出来。特别地，遮蔽气体可以再处理核X射线发射，产生窄的Fe K $α$线和康普顿反射峰。近年来，X射线从模糊环面反射的模型已经被计算出来;然而，尽管反射气体可能是尘埃，模型还没有考虑到尘埃对预测光谱的影响。我们研究这个问题，通过分析两组模型，有和没有灰尘的存在下，使用一维光电离代码多云。对一系列柱密度（$22 <{\rm log}[N_H(\rm cm^{-2})]< 24.5$）和氢密度（$6 <{\rm log}[n_H(\rm cm^{-3})]< 8$）进行计算。计算结果表明，尘埃的存在下，可以提高的Fe K $α$等效宽度（EW）在反射光谱的因素高达$\approx$ 8康普顿厚（CT）的气体和一个典型的ISM粒度分布。EW相对于反射连续谱的增强是由于由尘埃颗粒的各向异性散射行为引起的反射连续谱强度的降低。这种效应将是最相关的反射，从遥远的，主要是中性气体，是一个可能的解释活动星系核，显示出强大的Fe K $α$ EW和一个相对较弱的反射连续。我们的研究结果表明，它是一个重要的是要考虑到灰尘，而建模的X射线反射光谱，推断CT柱密度从观测到的Fe K $α$ EW可能并不总是有效的。需要多维度模型来充分探索影响的程度。
We present the systematic broadband X-ray spectral analysis of 52 Compton-thick ($24 \leq \log N_{\mathrm{H}}^{\mathrm{LOS}}/\mathrm{cm}^{-2}$) active galactic nucleus (CTAGN) candidates selected by the Swift/BAT all-sky hard X-ray survey observed with Chandra, XMM--Newton, Swift/XRT, Suzaku, and NuSTAR. The XMM--Newton data of 10 objects and the NuSTAR data of 15 objects are published for the first time. We use an X-ray spectral model from a clumpy torus (XClumpy) to determine the torus properties. As a result, the hydrogen column density along the line of sight $N_{\mathrm{H}}^{\mathrm{LOS}}…
We have analyzed the broadband X-ray spectra of active galactic nuclei (AGNs) in two "non-merging" luminous infrared galaxies (LIRGs) UGC 2608 and NGC 5135, utilizing the data of NuSTAR, Suzaku, XMM-Newton, and Chandra. Applying the X-ray clumpy-torus model (XCLUMPY: Tanimoto et al. 2019), we find that both sources have similar spectra characterized by Compton-thick (CT) absorption ($N_{\rm H} \sim$ 5-7 $\times$ $10^{24}$ cm$^{-2}$) and small torus angular width ($σ$ $<$ 20$^{\circ}$). The intrinsic 2-10 keV luminosities are $3.9^{+2.2}_{-1.7}$ $\times$ $10^{43}$ erg s$^{-1}$ (UGC 2608) and $2…
Unification Model of Active Galactic Nuclei by Photoionization Equilibrium Calculation Based on Radiative Hydrodynamic Simulations
Graduate School of Science and Engineering, Kagoshima University（鹿儿岛大学理工学研究科）；Research Center for Space and Cosmic Evolution, Ehime University（爱媛大学宇宙 evolution 研究中心）；Faculty of Science, Hokkaido University（北海道大学理学部）；Astronomical Institute, Tohoku University（东北大学天文学研究所）；Faculty of Natural Sciences, National Institute of Technology, Kure College（国立神户高等专门学校自然科学学部）；Graduate School of Science and Technology, Hirosaki University（弘前大学理工学研究科）；Department of Earth and Space Science, The University of Osaka（大阪大学地球空间科学系）
How complex is the obscuration in AGN? New clues from the Suzaku monitoring of the X-ray absorbers in NGC7582
我们提出了一个朱雀监测活动的塞弗特2星系，NGC 7582的结果。该源的特点是内吸收体的柱密度变化非常迅速（在甚至低于一天的时间尺度上），同时存在康普顿厚材料再处理时产生的恒定组分。最佳拟合场景意味着对统一模型的零阶视图进行重要修改。虽然为了产生恒定的康普顿反射分量和铁K $α$发射线，需要pc尺度的环面的存在，但在这个塞弗特2星系中，这不是沿着视线观察到的。另一方面，主连续谱的吸收是由于另一种材料，更接近BH，大约在BLR的距离，这可以产生观察到的快速光谱变化。最重要的是，$10^{22}$ cm $^{-2}$柱密度的持续存在可以归因于尘埃带的存在，在星系尺度上延伸，正如钱德拉先前所证实的那样。现在有越来越多的证据表明，活动星系核的复杂性可能是规则而不是例外。因此，我们建议修改统一模型，增加两个额外的吸收器/发射器的存在的环面。它们沿着视线的组合可以再现所有观察到的现象学。
Photoionized absorbers of outflowing gas are commonly found in the X-ray spectra of active galactic nuclei (AGN). While most of these absorbers are seldom significantly variable, some ionized obscurers have been increasingly found to substantially change their column density on a wide range of time scales. These $N_\text{H}$ variations are often considered as the signature of the clumpy nature of the absorbers. Here we present the analysis of a new Neil Gehrels Swift Observatory campaign of the type-1 quasar PG 1114+445, which was observed to investigate the time evolution of the multiphase ou…
We present a large compilation of reddening estimates from broad-line Balmer decrements for active galactic nuclei (AGNs) with measured X-ray column densities. The median reddening is E(B-V) ~ 0.77 +/- 0.10 for type-1 to type-1.9 AGNs with reported column densities. This is notably higher than the median reddening of AGNs from the SDSS. We attribute this to the selection bias of the SDSS towards blue AGNs. For other AGNs we find evidence of a publication bias against reporting low column densities. We find a significant correlation between N_H and E(B-V) but with a large scatter of +/- 1 dex (…
The NuSTAR View of Nearby Compton-thick AGN: The Cases of NGC 424, NGC 1320 and IC 2560
本文介绍了NuSTAR在3-79 keV波段观测到的三个Seyfert 2活动星系核NGC 424、NGC 1320和IC 2560的X射线光谱分析。高质量的硬X射线光谱允许在这些源中首次对康普顿反射分量进行详细建模。使用准同步NuSTAR和Swift/XRT数据，以及档案XMM-牛顿数据，我们发现，所有三个核被掩盖的康普顿厚的材料，柱密度超过~5 x $10^{24}$ cm $^{-2}$，和他们的X射线光谱超过3千电子伏的康普顿厚的材料上的反射的内在连续性占主导地位。由于非常高的遮蔽度，吸收的本征连续谱分量在任何源中的数据都不是正式要求的。我们通过反射光谱的形状来约束反射介质的内禀光子指数和柱密度。使用档案多波长数据，我们恢复的固有的X射线光度与宽带光谱能量分布一致。我们的研究结果是一致的反射介质是一个边缘上的cluerectorus具有相对较大的全球覆盖因子和整体反射效率的顺序为1%。由于明确确认的康普顿厚的性质的来源，我们调查是否有可能错过了康普顿厚AGN的常用选择标准，并探讨找到他们的高红移同行的可能性。
Toward the Standard Population Synthesis Model of the X-Ray Background: Evolution of X-Ray Luminosity and Absorption Functions of Active Galactic Nuclei Including Compton-Thick Populations
