We report sensitive Chandra X-ray non-detections of two unusual, luminous Iron Low-Ionization Broad Absorption Line Quasars (FeLoBALs). The observations do detect a non-BAL, wide-binary companion quasar to one of the FeLoBAL quasars. We combine X-ray-derived column density lower limits (assuming solar metallicity) with column densities measured from ultraviolet spectra and CLOUDY photoionization simulations to explore whether constant density slabs at broad line region densities can match the physical parameters of these two BAL outflows, and find that they cannot. In the "overlapping-trough" object SDSS J0300+0048, we measure the column density of the X-ray absorbing gas to be N_H >= 1.8 x 1024 cm-2. From the presence of Fe II UV78 absorption but lack of Fe II UV195/UV196 absorption, we infer the density in that part of the absorbing region to be n_e ~ 106 cm-3. We do find that a slab of gas at that density might be able to explain this object's absorption. In the Fe III-dominant object SDSS J2215-0045, the X-ray absorbing column density of N_H >= 3.4 x 1024 cm-2 is consistent with the Fe III-derived N_H >= 2 x 1022 cm-2 provided the ionization parameter is log U > 1.0 for both the n_e = 1011 cm-3 and n_e = 1012 cm-3 scenarios considered (such densities are required to produce Fe III absorption without Fe II absorption). However, the velocity width of the absorption rules out its being concentrated in a single slab at these densities. Instead, this object's spectrum can be explained by a low density, high ionization and high temperature disk wind that encounters and ablates higher density, lower ionization Fe III-emitting clumps.
无菌中微子是一种弱相互作用粒子，出现在标准粒子物理学的某些扩展框架中，自然符合暖暗物质候选粒子的性质。我们提出了一个深入的档案钱德拉观测威尔曼1，一个最黑暗的传说中的超微弱的矮星系，不包括在1.6-16千电子伏的质量范围内的55个pc的观察范围内的不育中微子的存在的分析。对钱德拉数据的光谱分析未能发现任何可能与暗物质粒子的辐射衰变有关的非仪器光谱特征。因此，我们建立上界的不育中微子参数空间，并讨论它的背景下，以前的测量。关于点源总体，我们在中心5弧分内识别出总共26个源，其极限0.5-2.0 keV X射线通量为6 x 10^{-16} erg cm^{-2} s^{-1}。虽然这些来源中的一些可能是威尔曼1的正式成员，但我们没有发现任何突出的证据来证明明亮的X射线源的不寻常人口或人口稠密的集群核心。事实上，整个X射线族群可以用背景活动星系核和/或与威尔曼1号无关的前景恒星来解释。最后，讨论了SDSS DR 7星表中的X射线点状星群与光源的可能联系。
The unrivalled spatial resolution of the Chandra X-ray observatory has allowed many breakthroughs to be made in high energy astrophysics. Here we explore applications of Gaussian Gradient Magnitude (GGM) filtering to X-ray data, which dramatically improves the clarity of surface brightness edges in X-ray observations, and maps gradients in X-ray surface brightness over a range of spatial scales. In galaxy clusters, we find that this method is able to reveal remarkable substructure behind the cold fronts in Abell 2142 and Abell 496, possibly the result of Kelvin Helmholtz instabilities. In Abel…
Abell 2146 consists of two galaxy clusters that have recently collided close to the plane of the sky, and it is unique in showing two large shocks on $\textit{Chandra X-ray Observatory}$ images. With an early stage merger, shortly after first core passage, one would expect the cluster galaxies and the dark matter to be leading the X-ray emitting plasma. In this regard, the cluster Abell 2146-A is very unusual in that the X-ray cool core appears to lead, rather than lag, the Brightest Cluster Galaxy (BCG) in their trajectories. Here we present a strong lensing analysis of multiple image systems…
Merging galaxy clusters leave long-lasting signatures on the baryonic and non-baryonic cluster constituents, including shock fronts, cold fronts, X-ray substructure, radio halos, and offsets between the dark matter and the gas components. Using observations from Chandra, the Jansky Very Large Array, the Giant Metrewave Radio Telescope, and the Hubble Space Telescope, we present a multiwavelength analysis of the merging Frontier Fields cluster MACS J0416.1-2403 (z=0.396), which consists of a NE and a SW subclusters whose cores are separated on the sky by ~250 kpc. We find that the NE subcluster…
We present results from a very deep (650 ks) Chandra X-ray observation of the galaxy group NGC~5813, the deepest Chandra observation of a galaxy group to date. Earlier observations showed two pairs of cavities distributed roughly collinearly, with each pair associated with an elliptical shock front. The new observations confirm a third pair of outer cavities, collinear with the other pairs, and reveal an associated outer outburst shock at ~30 kpc. This system is therefore unique in exhibiting three cavity pairs, each associated with an unambiguous AGN outburst shock front. The implied mean kin…
Radiation pressure, absorption and AGN feedback in the Chandra Deep Fields
活动星系核（AGN）中央引擎周围存在吸收气体是这些天体的共同特征。最近的工作着眼于气体的尘埃成分的影响，以及它如何提高辐射压力，使含尘气体可以有一个较低的有效爱丁顿限制比电离气体。在这项工作中，我们使用多波长的数据和X射线光谱从2毫秒曝光的钱德拉深场北和钱德拉深场南调查，以确定活动星系核的爱丁顿比和氢柱密度。它们的分布进行比较，当考虑到尘埃和气体之间的耦合预测。我们的最终样本包括来自两个领域的234个对象，最大和最深的AGN样本，这种比较已经取得了最新的。我们发现，样本中的活动星系核大多倾向于在低爱丁顿比（通常在1 e-4和1 e-1之间）和高柱密度（> 1 e 22 cm^-2）下发现，而黑洞的质量在~ 1 e 8和1 e 9太阳质量之间。它们的分布与增强辐射压力模型的预期一致，避开了我们预测存在外流的区域。我们还研究了活动星系核辐射压力和引力势之间的平衡如何影响星系核球中云的行为，并描述了一种增强的辐射压力可以导致黑洞/星系标度关系的基本平面的情况。
