X-ray obscuration and obscured AGN in the local universe
X-ray obscuration and obscured AGN in the local universe
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DOI：
10.1051/0004-6361:20053643
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发表时间：
2005-08
影响因子：
6.5
通讯作者：
M. Guainazzi;G. Matt;G. Perola
中科院分区：
文献类型：
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作者：
M. Guainazzi;G. Matt;G. Perola
我们讨论了49个本地（$z钱德拉和XMM牛顿观测，其中产生25（22）个新的X射线探测在0.5-2 keV（2-10 keV）的能带的X射线性质。我们的样品覆盖了2-10 keV观测通量F 2-10的范围，从3 × 10^{-11}$到6 × 10^{-15}$ erg cm-2 s-1。可能被康普顿厚度的物质遮蔽的物体的百分比（柱密度，$N_{\rm H} \ge \sigma_t^{-1} \simeq 1.6 \times 10^{24}$ cm-2）为$\simeq $50%，对于$\log\达到$\simeq $80%，（F_{2-10}）α荧光铁谱线具有较大的等效宽度（${\itEW} > 0.6$ keV），在我们的样品中是常见的（6个新的检测，置信水平≥ 2 σ）。它们被解释为由于光学厚材料的被照射侧的反射。我们证实了WFC 2图像中~100-pc尺度核尘埃的存在与康普顿薄遮蔽之间的相关性。我们解释这种相关性是由于大覆盖部分的气体与尘埃带。高度模糊的活动星系核的X射线谱总是呈现出一个突出的软过量发射以上的硬X射线分量的外推。这种软分量可以占整个X射线能量预算的很大一部分。由于这一成分通常是不被遮蔽的，因此很可能产生于扩展的气体结构中，如果使用标准的X射线颜色来对它们进行分类，那么它可能会导致严重低估被吸收的活动星系核中的核遮蔽。作为我们研究的一个副产品，我们报告发现了一个软X射线，发光（$\simeq$7 $\，\times\，10^{40}$ erg s-1）晕嵌入相互作用的星系对Mkn 266。
We discuss the X-ray properties of 49 local ($z Chandra and XMM-Newton observations, which yield 25 (22) new X-ray detections in the 0.5–2 keV (2–10 keV) energy band. Our sample covers a range in the 2–10 keV observed flux, F 2-10 , from $3 \times 10^{-11}$ to $6 \times 10^{-15}$ erg cm -2 s -1 . The percentage of objects that are likely obscured by Compton-thick matter (column density, $N_{\rm H} \ge \sigma_t^{-1} \simeq 1.6 \times 10^{24}$ cm -2 ) is $\simeq$50%, and reaches $\simeq$80% for $\log\, (F_{2-10}) α fluorescent iron lines with large Equivalent Width (${\it EW} > 0.6$ keV) are common in our sample (6 new detections at a confidence level ≥ 2 σ ). They are explained as due to reflection off the illuminated side of optically thick material. We confirm a correlation between the presence of a ~100-pc scale nuclear dust in the WFC2 images and Compton-thin obscuration. We interpret this correlation as due to the large covering fraction of gas associated with the dust lanes. The X-ray spectra of highly obscured AGN invariably present a prominent soft excess emission above the extrapolation of the hard X-ray component. This soft component can account for a very large fraction of the overall X-ray energy budget. As this component is generally unobscured – and therefore likely produced in extended gas structures – it may lead to a severe underestimation of the nuclear obscuration in $z \sim 1$ absorbed AGN, if standard X-ray colors are used to classify them. As a by-product of our study, we report the discovery of a soft X-ray, luminous ($\simeq$7$\,\times\, 10^{40}$ erg s -1 ) halo embedding the interacting galaxy pair Mkn 266.