We present a study of the core of the Fe Ka emission line at ~6.4 keV in a sample of type II Seyfert galaxies observed by the Chandra High Energy Grating (HEG). The sample consists of 29 observations of 10 unique sources. We present measurements of the Fe Ka line parameters with the highest spectral resolution currently available. In particular, we derive the most robust intrinsic line widths for some of the sources in the sample to date. We obtained a weighted mean FWHM of 2000 \pm 160 km/s for 8 out of 10 sources (the remaining sources had insufficient signal-to-noise). From a comparison with the optical emission-line widths obtained from spectropolarimetric observations, we found that the location of Fe Ka line-emitting material is a factor of ~0.7-11 times the size of the optical BLR. Furthermore, compared to 13 type I AGNs for which the best Fe Ka line FWHM constraints were obtained, we found no difference in the FWHM distribution or the mean FWHM, and this conclusion is independent of the central black hole mass. This result suggests that the bulk of the Fe Ka line emission may originate from a universal region at the same radius with respect to the gravitational radius, ~30,000 Rg on average. By examining the correlation between the Fe Ka luminosity and the [O IV] line luminosity, we found a marginal difference in the Fe K line flux between type I and type II AGNs, but the spread in the ratio of L(Fe) to L([O IV]) is about two orders of magnitude. Our results confirm the theoretical expectation that the Fe Ka emission-line luminosity cannot trivially be used as a proxy of the intrinsic AGN luminosity, unless a detailed comparison of the data with proper models is applied.
Warm absorbers in X-rays (WAX), a comprehensive high resolution grating spectral study of a sample of Seyfert galaxies: I. A global view and frequency of occurrence of warm absorbers
我们提出的结果从均匀分析的宽带0.3-10 keV的CCD分辨率,以及软X射线高分辨率光栅光谱的硬X射线通量有限的样品26塞弗特星系观测XMM-牛顿。我们的目标是沿着活动核的视线来研究热吸收体(WA)的性质。我们在样本源的$65\%$中显著检测到WA。我们的研究结果是一致的WAs存在于至少一半的塞弗特星系在附近的宇宙中,与以前的估计。我们发现在$0.5<\logξ<1.5$的范围内,我们解释为WA云的热不稳定区域的电离参数的分布的差距。这可能表明,暖吸收流可能是由离散云的clusterical分布,而不是一个连续的介质。具有宽的Fe K $α$线的源的WA柱密度的分布类似于那些没有加宽的发射线的源。因此,检测到的宽Fe K $α$发射线是真实的,而不是软X射线中电离吸收的伪影。WA参数显示它们之间没有相关性,除了电离参数与柱密度。$\logξ$与$\log v_{\rm out}$线性回归($0.12\pm 0.03$)的浅斜率与辐射或磁流体动力驱动风预测的标度律不一致。我们的研究结果还表明,WA和超快速外流(UFO)并不代表同一天体物理系统的极端表现。
High-resolution X-ray spectroscopy of the low and high states of the Seyfert 1 galaxy NGC 4051 with Chandra LETGS
方法.本文分析了Chandra低能透射光栅光谱仪的两个观测结果。我们研究了光谱响应突然通量减少的一个因素,这发生在第二次观察。结果我们检测到一个高度电离的吸收组件的流出速度为-4670公里/秒,在塞弗特1星系中观察到的最高流出速度的组件之一。该光谱包含一个相对论O VIII Ly α线,和四个吸收组件跨越范围的电离参数XI在0.07和3.19之间。在低态出现了产生CVI和CV辐射复合连续谱的发射分量。黑体温度随着第二次观测中观测到的通量的下降而下降。结论.对于所有的吸收器组件,我们排除了电离参数线性响应通量的减少了5倍。吸收体的可变性表明,四个检测到的组分中至少有三个位于0.02-1 pc的范围内。删节
Axion-Like Particles (ALPs) are predicted by several Beyond the Standard Model theories, in particular, string theory. In the presence of an external magnetic field perpendicular to the direction of propagation, ALPs can couple to photons. Therefore, if an X-ray source is viewed through a magnetised plasma, such as a luminous quasar in a galaxy cluster, we may expect spectral distortions that are well described by photon-ALP oscillations. We present a $571 \ \mathrm{ks}$ combined High and Low Energy Transmission Grating (HETG/LETG) Chandra observation of the powerful radio-quiet quasar H1821+6…
Axions/axion-like particles (ALPs) are a well motivated extension of the Standard Model and are generic within String Theory. The X-ray transparency of the intracluster medium (ICM) in galaxy clusters is a powerful probe of light ALPs (with mass $<10^{-11}\,{\rm eV}$); as X-ray photons from an embedded or background source propagate through the magnetized ICM, they may undergo energy-dependent quantum mechanical conversion into ALPs (and vice versa), imprinting distortions on the X-ray spectrum. We present Chandra data for the active galactic nucleus NGC1275 at the center of the Perseus cluste…