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arXiv 1003.1790astro-ph.HEastro-ph.GA
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活动星系核中Fe K $α$线的核心：一个扩展的Chandra高能光栅样品

The Cores of the Fe K$α$ Lines in Active Galactic Nuclei: an Extended Chandra High Energy Grating Sample

X. W. Shu, T. Yaqoob, J. X. Wang

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54 pages, 7 figures, and 4 tables, to appear in ApJ Supplement Series
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摘要：

利用钱德拉高能光栅（HEG）观测到的较大样本，对Yaqoob & Padmanabhan（2004）报道的Seyfert星系中\sim 6.4 keV的Fe K $α$发射线核心的研究进行了扩展。虽然严重模糊的活动星系核（AGN）被排除在样本之外，这些数据提供了一些最高精度的测量的峰值能量的Fe K $α$线，和最高的光谱分辨率测量的核心的宽度的线在unobscured和适度模糊（$N_{H}<10^{23} \ \rm cm^{-2}$）塞弗特星系的日期。在33个源中检测到Fe K $α$线，并在32个源中约束其质心能量。在27个数据源中，数据的统计质量足以产生FWHM的测量值。我们发现，线质心能量的分布在中性Fe的值附近有很强的峰值，超过80%的观测值在6.38- 6.43keV范围内。包括统计误差，32个源中的30个（$\sim 94%$）具有在6.35- 6.47 keV范围内的线质心能量。在可以测量非零下限的观测值中，平均等效宽度为$53 \pm 3eV. The mean FWHM from the subsample of 27 sources was $ 2060 \pm 230 \ \rm km \ s^{-1} $. The mean EW and FWHM are somewhat higher when multiple observations for a given source are averaged. From a comparison with the H$ β $ optical emission-line widths (or, for one source, Br$ α $), we find that there is no universal location of the Fe K$ α $ line-emitting region relative to the optical BLR. We confirm the presence of the X-ray Baldwin effect, an anti-correlation between the Fe K$ α $ line EW and X-ray continuum luminosity. The HEG data have enabled isolation of this effect to the narrow core of the Fe K$ α$线。

英文摘要：

We extend the study of the core of the Fe K$α$ emission line at \sim 6.4 keV in Seyfert galaxies reported in Yaqoob & Padmanabhan (2004) using a larger sample observed by the Chandra High Energy Grating (HEG). Whilst heavily obscured active galactic nuclei (AGNs) are excluded from the sample, these data offer some of the highest precision measurements of the peak energy of the Fe K$α$ line, and the highest spectral resolution measurements of the width of the core of the line in unobscured and moderately obscured ($N_{H}<10^{23} \ \rm cm^{-2}$) Seyfert galaxies to date. The Fe K$α$ line is detected in 33 sources, and its centroid energy is constrained in 32 sources. In 27 sources the statistical quality of the data is good enough to yield measurements of the FWHM. We find that the distribution in the line centroid energy is strongly peaked around the value for neutral Fe, with over 80% of the observations giving values in the range 6.38--6.43 keV. Including statistical errors, 30 out of 32 sources ($\sim 94%$) have a line centroid energy in the range 6.35--6.47 keV. The mean equivalent width, amongst the observations in which a non-zero lower limit could be measured, was $53 \pm 3eV. The mean FWHM from the subsample of 27 sources was $2060 \pm 230 \ \rm km \ s^{-1}$. The mean EW and FWHM are somewhat higher when multiple observations for a given source are averaged. From a comparison with the H$β$ optical emission-line widths (or, for one source, Br$α$), we find that there is no universal location of the Fe K$α$ line-emitting region relative to the optical BLR. We confirm the presence of the X-ray Baldwin effect, an anti-correlation between the Fe K$α$ line EW and X-ray continuum luminosity. The HEG data have enabled isolation of this effect to the narrow core of the Fe K$α$ line.

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