Probing the Disk–Corona Systems and Broad-line Regions of Changing-look Quasars with X-Ray and Optical Observations
Probing the Disk–Corona Systems and Broad-line Regions of Changing-look Quasars with X-Ray and Optical Observations
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DOI：
10.3847/1538-4357/abeb17
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发表时间：
2021-03
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通讯作者：
Xiangyu Jin;J. Ruan;D. Haggard;Marie-Joëlle Gingras;Joseph Hountalas;C. MacLeod;S. Anderson;Anh Doan;M. Eracleous;P. Green;J. Runnoe
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作者：
Xiangyu Jin;J. Ruan;D. Haggard;Marie-Joëlle Gingras;Joseph Hountalas;C. MacLeod;S. Anderson;Anh Doan;M. Eracleous;P. Green;J. Runnoe
“变脸”类星体是一类新的高度可变的活动星系核，它们在令人惊讶的短短几年时间内改变了光谱类型。这一现象的起源尚有争议，但很可能反映了吸积流的一些变化。为了研究这些天体中的盘状日冕系统，我们测量了之前发现的两个或更多个历元的10个变貌类星体的光学/紫外-X射线光谱指数(αOX)和艾丁顿比(λEDD)。通过将这些数据与基于X射线双星行为的模拟结果进行比较，我们发现在1%的爱丁顿比以下的光谱指数可能有相似之处。我们进一步研究了变貌类星体在光谱类型改变前后的爱丁顿比，发现变貌类星体在宽的发射线消失/出现时越过了1%的爱丁顿比边界。这与圆盘-风模型作为宽发射线的起源是一致的。
“Changing-look” quasars are a new class of highly variable active galactic nuclei that have changed their spectral type over surprisingly short timescales of just a few years. The origin of this phenomenon is debated, but is likely to reflect some change in the accretion flow. To investigate the disk–corona systems in these objects, we measure optical/UV–X-ray spectral indices ( αOX ) and Eddington ratios ( λEdd ) of 10 previously discovered changing-look quasars at two or more epochs. By comparing these data with simulated results based on the behavior of X-ray binaries, we find possible similarities in spectral indices below the 1% Eddington ratio. We further investigate the Eddington ratios of changing-look quasars before and after their spectral type changes, and find that changing-look quasars cross the 1% Eddington ratio boundary when their broad emission lines disappear/emerge. This is consistent with the disk-wind model as the origin of broad emission lines.