Microlensing variability in the gravitationally lensed quasar QSO $2237+0305 \equiv$ the Einstein Cross
Microlensing variability in the gravitationally lensed quasar QSO $2237+0305 \equiv$ the Einstein Cross
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DOI：
10.22323/1.054.0051
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发表时间：
2008-08
影响因子：
4.8
通讯作者：
A. Eigenbrod
中科院分区：
文献类型：
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作者：
A. Eigenbrod
我们提出的第一个长期（2.2年）的引力透镜类星体，即爱因斯坦十字类星体2237+0305光谱监测的结果。本文的目的是提出观测事实，以便在后续论文中与理论模型进行比较，以约束源类星体的内部结构。我们空间反卷积深VLT/FORS 1光谱，准确地分离光谱的透镜星系的类星体图像的光谱。对2004年10月至2006年12月的31历元的58个观测数据进行了精确的交叉定标，并对与类星体同时观测的不变前景星进行了交叉定标。类星体的光谱被进一步分解成一个连续谱分量和几条宽的发射线，以推断这些光谱分量的变化。我们在类星体图像A和B中发现了显著的微透镜事件，而图像C和D在几个月的时间尺度上几乎是静止的。在图像A的连续区中观察到最强的变化。它们的振幅在蓝色（0.7等）比红色（0.5等）大，与吸积盘的微透镜一致。宽发射线的强度和轮廓的变化也有报道，最突出的是在C III和C IV发射线的中心的翅膀。在2006年6月观察到的类星体图像A中的强微透镜事件期间，C iii的宽分量比窄分量放大得更高。此外，具有较高电离势的发射线比具有较低电离势的发射线更放大，这与用混响映射获得的结果一致。最后，我们发现类星体图像之间的透镜对V波段的微分消光在0.1 - 0.3 mag.的范围内。
We present the results of the first long-term (2.2 years) spectroscopic monitoring of a gravitationally lensed quasar, namely the Einstein Cross QSO 2237+0305. The goal of this paper is to present the observational facts to be compared in follow-up papers with theoretical models to constrain the inner structure of the source quasar. We spatially deconvolve deep VLT/FORS1 spectra to accurately separate the spectrum of the lensing galaxy from the spectra of the quasar images. Accurate cross-calibration of the 58 observations at 31-epoch from October 2004 to December 2006 is carried out with non-variable foreground stars observed simultaneously with the quasar. The quasar spectra are further decomposed into a continuum component and several broad emission lines to infer the variations of these spectral components. We find prominent microlensing events in the quasar images A and B, while images C and D are almost quiescent on a timescale of a few months. The strongest variations are observed in the continuum of image A. Their amplitude is larger in the blue (0.7 mag) than in the red (0.5 mag), consistent with microlensing of an accretion disk. Variations in the intensity and profile of the broad emission lines are also reported, most prominently in the wings of the C iii and center of the C iv emission lines. During a strong microlensing episode observed in June 2006 in quasar image A, the broad component of the C iii is more highly magnified than the narrow component. In addition, the emission lines with higher ionization potentials are more magnified than the lines with lower ionization potentials, consistent with the results obtained with reverberation mapping. Finally, we find that the V-band differential extinction by the lens, between the quasar images, is in the range 0.1−0.3 mag.