X-Ray Emission from Seyfert 2 Galaxies with Optical Polarized Broad Lines
X-Ray Emission from Seyfert 2 Galaxies with Optical Polarized Broad Lines
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DOI：
10.1086/309516
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发表时间：
2000-06
期刊：
影响因子：
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通讯作者：
H. Awaki;S. Ueno;Y. Taniguchi;K. Weaver
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作者：
H. Awaki;S. Ueno;Y. Taniguchi;K. Weaver
我们分析了用x射线卫星ASCA观测到的6个Seyfert 2星系的0.5-10 keV光谱：Mrk 3、Mrk 348、Mrk 1210、Mrk 477、NGC 7212和Was 49b。这些星系是根据它们拥有的光偏振宽频线而选择的。在2-10 keV波段，它们的光谱被大量吸收，2-10 keV吸收校正的x射线光度范围为1042至1043 ergs -1。观测到的x射线发射通常只有根据已知红外和Hβ光度预测的1/10左右。如果核活动的相当一部分完全被沿着我们的视线到原子核的厚物质挡住，这种明显的x射线弱可以被理解。所有这些星系都有明显的软x射线发射，其起源似乎是其核发射的散射光。基于这一假设，我们估计x射线的典型散射效率约为10%。这个效率比普通的塞弗特2星系所发现的几个百分点要大，没有光学偏振宽线的报道。高散射效率最好的解释是硬x射线亮度的明显减弱，而不是软波段中异常强的散射光。假设康普顿散射占硬x射线光谱的主导地位，而不是纯粹吸收的核连续体，当我们利用本征光度估计散射效率时，效率可以更低，与普通Seyfert 2星系的效率相似。由于我们的样本与普通Seyfert 2星系之间的差异可以用观测角度的差异来解释，相似的散射效率表明存在一个比假定的尘埃环更大的散射区域。
We analyze the 0.5-10 keV spectra of six Seyfert 2 galaxies observed with the X-ray satellite ASCA: Mrk 3, Mrk 348, Mrk 1210, Mrk 477, NGC 7212, and Was 49b. These galaxies were selected based on their possession of optical polarized broad lines. In the 2-10 keV band, their spectra are heavily absorbed, with 2-10 keV absorption-corrected X-ray luminosities ranging from 1042 to 1043 ergs s-1. The observed X-ray emission is generally only about 1/10 that predicted based on their known infrared and Hβ luminosities. This apparent X-ray weakness can be understood if a considerable fraction of the nuclear activity is completely blocked from view by thick matter along our line of sight to the nucleus. All of these galaxies possess significant soft X-ray emission whose origin appears to be scattered light from their nuclear emission. Based on this hypothesis, we estimate a typical scattering efficiency for X-rays to be about 10%. This efficiency is larger than the few percent found for ordinary Seyfert 2 galaxies with no report of optical polarized broad lines. A large scattering efficiency is best explained by an apparent weakness of the hard X-ray luminosity rather than unusually strong scattered light in the soft band. When we estimate the scattering efficiency using the intrinsic luminosity derived assuming that Compton scattering dominates the hard X-ray spectrum, as opposed to a purely absorbed nuclear continuum, the efficiency can be less and is similar to that of ordinary Seyfert 2 galaxies. Since the difference between our sample and ordinary Seyfert 2 galaxies can be explained by the difference of viewing angle, the similar scattering efficiency suggests the existence of a scattering region that is larger than the putative dusty torus.