论文标题
光谱型的光谱型光谱法MRK MRK 1018
Spectropolarimetry of the changing-look active galactic nucleus Mrk 1018
论文作者
论文摘要
我们在更换外观活跃的银河核（AGN）MRK 1018的可见波长处获得了新的光谱观测。AGN直接频谱显示出非常弱的连续体，微弱的H $β$和H $α$发射线微弱。这两条线都可以与单个非常宽的发射线组件相吻合，该线路的最大宽度为FWHM $ \ simeq $ 7200 km S $^{ - 1} $，没有证据表明先前检测到的3000 km S $^{ - 1} $ - 宽的组件。尽管这与开普勒磁盘中的线形成一致，但线曲线变异性表明宽发射线区域可能更为复杂。 MRK 1018的连续极化低；与过去的明亮状态相比，目前的淡淡状态并不高，证实灰尘遮挡不是外观变化起源的机制。 H $α$线的极化曲线是不对称的，没有极化角度旋转，这可能会揭示极性流出中的线形成。另外，极化轮廓可能是直接光和极化光之间的时间延迟的结果。有趣的是，未观察到在超级二元黑洞周围发出的宽线预测的极化特征。
We have obtained new spectropolarimetric observations at visible wavelengths of the changing-look active galactic nucleus (AGN) Mrk 1018. The AGN direct spectrum shows an extremely weak continuum with faint broad H$β$ and H$α$ emission lines. Both lines can be fit with a single very broad emission line component of full width at half maximum FWHM $\simeq$ 7200 km s$^{-1}$, with no evidence of the additional 3000 km s$^{-1}$-wide component that was previously detected. While this is in agreement with line formation in a Keplerian disk, the line profile variability suggests that the broad emission line region is likely more complex. The continuum polarization of Mrk 1018 is low; it is not higher in the current faint state compared to the past bright state, confirming that dust obscuration is not the mechanism at the origin of the change of look. The polarization profile of the H$α$ line is asymmetric with no rotation of the polarization angle, which possibly reveals line formation in a polar outflow. Alternatively, the polarization profile may be the consequence of a time delay between the direct and the polarized light. Interestingly, the polarization signatures predicted for broad lines emitted around supermassive binary black holes are not observed.
