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arXiv 1104.3676astro-ph.COastro-ph.GAastro-ph.HE
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Seyfert Galerkin中的反射和AGN的统一模型

Reflection in Seyfert Galaxies and the Unified Model of AGN

Claudio Ricci, Roland Walter, Thierry J. -L. Courvoisier, Stephane Paltani

摘要:

本文对塞弗特星系的平均硬X射线谱进行了深入的研究。我们分析了在z<0.2时检测到的所有165个塞弗特星系的所有公共INTEGRAL IBIS/ISGRI数据。我们的最终样品包括44个Seyfert 1,29个Seyfert 1.5,78个Seyfert 2和14个Narrow Line Seyfert 1。在17- 250 keV能量范围内,我们导出了每个子样品的平均硬X射线谱。所有类型的塞弗特星系平均表现出相同的核连续谱,正如零级统一模型所预见的那样,截止能量Ec> 200 keV,光子指数Gamma ~1.8。康普顿薄Seyfert 2的反射分量比Seyfert 1和Seyfert 1.5强。大部分的反射是由于轻微的模糊(10^23 cm^-2 < NH < 10^24 cm^-2)塞弗特2型,反射分量明显更强(R=2.2^{+4.5}_{-1.1})比Seyfert 1(R<=0.4)、Seyfert 1.5(R<= 0.4)和轻度模糊(NH < 10^23 cm^-2)的Seyfert 2(R<=0.5)好。这不能简单地用统一模型来解释。在轻度模糊的塞弗特2中,吸收器/反射器可能覆盖了X射线源的很大一部分,并且有康普顿厚度的物质团块。在轻度模糊的塞弗特2光谱中发现的大反射减少了解释宇宙X射线背景峰值所需的康普顿厚度物体的数量。我们的结果是一致的康普顿厚源的分数为~ 10%。有和没有偏振宽线的Seyfert 2的光谱没有显示出显着的差异,两个样品之间的唯一区别是有偏振宽线的Seyfert 2的更高的硬X射线和测热光度。窄线Seyfert 1的平均硬X射线谱比Seyfert 1和Seyfert 1.5的陡,可能是由于截止能量较低。

英文摘要:

We present a deep study of the average hard X-ray spectra of Seyfert galaxies. We analyzed all public INTEGRAL IBIS/ISGRI data available on all the 165 Seyfert galaxies detected at z<0.2. Our final sample consists of 44 Seyfert 1's, 29 Seyfert 1.5's, 78 Seyfert 2's, and 14 Narrow Line Seyfert 1's. We derived the average hard X-ray spectrum of each subsample in the 17-250keV energy range. All classes of Seyfert galaxies show on average the same nuclear continuum, as foreseen by the zeroth order unified model, with a cut-off energy of Ec>200keV, and a photon index of Gamma ~1.8. Compton-thin Seyfert 2's show a reflection component stronger than Seyfert 1's and Seyfert 1.5's. Most of this reflection is due to mildly obscured (10^23 cm^-2 < NH < 10^24 cm^-2) Seyfert 2's, which have a significantly stronger reflection component (R=2.2^{+4.5}_{-1.1}) than Seyfert 1's (R<=0.4), Seyfert 1.5's (R<= 0.4) and lightly obscured (NH < 10^23 cm^-2) Seyfert 2's (R<=0.5). This cannot be explained easily by the unified model. The absorber/reflector in mildly obscured Seyfert 2's might cover a large fraction of the X-ray source, and have clumps of Compton-thick material. The large reflection found in the spectrum of mildly obscured Seyfert 2's reduces the amount of Compton-thick objects needed to explain the peak of the cosmic X-ray background. Our results are consistent with the fraction of Compton-thick sources being ~10%. The spectra of Seyfert 2's with and without polarized broad lines do not show significant differences, the only difference between the two samples being the higher hard X-ray and bolometric luminosity of Seyfert 2's with polarized broad lines. The average hard X-ray spectrum of Narrow line Seyfert 1's is steeper than those of Seyfert 1's and Seyfert 1.5's, probably due to a lower energy of the cutoff.

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