The broad iron K emission line in the Seyfert 2 galaxy IRAS 18325-5926
The broad iron K emission line in the Seyfert 2 galaxy IRAS 18325-5926
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DOI：
10.1093/mnras/279.3.837
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发表时间：
1996-04
影响因子：
4.8
通讯作者：
K. Iwasawa;A. Fabian;R. Mushotzky;W. N. Brandt;H. Awaki;H. Kunieda
中科院分区：
文献类型：
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作者：
K. Iwasawa;A. Fabian;R. Mushotzky;W. N. Brandt;H. Awaki;H. Kunieda
本文报道在Seyfert 2星系IRAS 18325 - 5926的ASCA X射线谱中探测到一条非常宽的铁Kα发射线。该线很强，等效宽度EW = 500-800 eV，其轮廓在6.9 keV处达到峰值，并向下倾斜至4 keV。蓝峰的能量明显高于许多活动星系中的6.4 keV的静止能量，这是从冷物质中产生的铁Kα线所预期的。如果在黑洞周围的冷吸积盘中，线能量的宽度和位移是由多普勒效应和相对论效应引起的，则该盘具有中等倾角i= 40°-50°。对于大的等效宽度，一个合理的解释是铁的超太阳丰度;这也解释了为什么没有显著的反射峰。线轮廓也可以解释为非常接近中心物体的高度电离物质的发射。然而，缺乏深铁K吸收边的Gingaspectrum是不一致的，这种interpretation.We验证，在104秒的时间尺度上的快速X射线的变化是常见的，在这个对象中，使用ASCA和ROSAT观测是部分同时进行的。使用组合ASCA和ROSAT PSPC数据的光谱变异性的研究表明，X射线通量的变化主要发生在1千电子伏以上，并建议一个稳定的，或至少少变，低于1千电子伏的组件。它应该位于核遮蔽区之外。
We report the detection of a very broad iron Kα emission line in the ASCA X-ray spectrum of the Seyfert 2 galaxy IRAS 18325 — 5926. The line is strong, with an equivalent widthEW= 500–800 eV, and its profile is peaked at 6.9 keV and skewed down to 4 keV. The energy of the blue peak of the line is significantly higher than the rest-energy of 6.4 keV seen in many active galaxies, which is expected from an iron Kα line arising in cold matter. If the breadth and shift of the line energy are caused by Doppler and relativistic effects in a cold accretion disc about a black hole, then the disc has an intermediate inclination,i= 40°-50°. A plausible interpretation for the large equivalent width is a supersolar abundance of iron; this also accounts for the lack of a significant reflection hump. The line profile can also be explained by emission from highly ionized matter very close to the central object. However, the lack of a deep iron K absorption edge in theGingaspectrum is inconsistent with this interpretation.We verify that fast X-ray variability on a time-scale of 104s is common in this object, usingASCAandROSATobservations which are partially simultaneous. A study of spectral variability using combinedASCAand ROSAT PSPC data reveals that the X-ray flux change occurred mainly above 1 keV, and suggests a stable, or at least less-variable, component below 1 keV. It should lie outside the nuclear obscuration region.