XMM-Newton Spectroscopy of the Highly Polarized and Luminous Broad Absorption Line Quasar CSO 755
XMM-Newton Spectroscopy of the Highly Polarized and Luminous Broad Absorption Line Quasar CSO 755
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高偏振和发光宽吸收线类星体 CSO 755 的 XMM-牛顿光谱
DOI：
10.1086/497830
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Mpe
中科院分区：
文献类型：
--
作者：
O. Shemmer;W. Brandt;S. Gallagher;C. Vignali;T. Boller;G. Chartas;A. C. Psu;Ucla;Inaf ;Mpe
本文介绍了XMM-Newton对高光偏振宽吸收线类星体（BALQSO） CSO 755的观测结果。通过分析其总共约3000个光子的x射线光谱，我们发现该源具有典型射电安静类星体的x射线连续体，光子指数Γ = 1.83，相当平坦（x射线明亮）的本征光学- x射线光谱斜率αox = -1.51。源显示出本征吸收的证据，用中性吸收模型拟合光谱得到柱密度为NH ~ 1.2 × 1022 cm-2；这是balqso测量到的最低x射线柱之一。我们在x射线光谱中没有发现任何其他具有重要意义的吸收特征。我们设定了中性（电离）Fe - k - α线的静帧等效宽度上限，≤180 eV(≤120 eV)，康普顿反射分量参数上限R≤0.2，这表明来自光源的大部分x射线都是直接观测到的，而不是被散射或反射；这也得到了我们测量的相对平坦的内征αox的支持。排除了大部分x射线通量由于高水平的紫外光偏振而散射的可能性。考虑到文献中46个balqso的数据，包括CSO 755，我们发现balqso的紫外光学连续偏振水平与它们的任何x射线性质都无关。源中缺乏显著的短期和长期x射线通量变化可能归因于CSO 755中的大黑洞质量。我们注意到另一个发光的BALQSO， PG 2112+059，具有类似的浅C IV BALs和中等x射线吸收。
We present the results from XMM-Newton observations of the highly optically polarized broad absorption line quasar (BALQSO) CSO 755. By analyzing its X-ray spectrum with a total of ∼3000 photons, we find that this source has the X-ray continuum of a typical radio-quiet quasar, with a photon index of Γ = 1.83 and a rather flat (X-ray bright) intrinsic optical–X-ray spectral slope of αox = -1.51. The source shows evidence for intrinsic absorption, and fitting the spectrum with a neutral-absorption model gives a column density of NH ∼ 1.2 × 1022 cm-2; this is among the lowest X-ray columns measured for BALQSOs. We do not detect, with high significance, any other absorption features in the X-ray spectrum. We place upper limits on the rest-frame equivalent width of a neutral (ionized) Fe Kα line, ≤180 eV (≤120 eV), and on the Compton-reflection component parameter, R ≤ 0.2, suggesting that most of the X-rays from the source are directly observed rather than being scattered or reflected; this is also supported by the relatively flat intrinsic αox we measure. The possibility that most of the X-ray flux is scattered due to the high level of UV-optical polarization is ruled out. Considering data for 46 BALQSOs from the literature, including CSO 755, we have found that the UV-optical continuum polarization level of BALQSOs is not correlated with any of their X-ray properties. A lack of significant short- and long-term X-ray flux variations in the source may be attributed to a large black hole mass in CSO 755. We note that another luminous BALQSO, PG 2112+059, has both similar shallow C IV BALs and moderate X-ray absorption.