Disentangling microlensing and differential extinction in the double QSO HE 0512–3329

Disentangling microlensing and differential extinction in the double QSO HE 0512–3329
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解开双 QSO HE 0512–3329 中的微透镜和微分消光

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发表时间：
2003
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通讯作者：
Lawrence Livermore National Laboratory
Lawrence Livermore National Laboratory
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作者：
O. Wucknitz;L. Wisotzki;S. López;M. P. U. Potsdam;A. Potsdam;U. Chile;Santiago;Lawrence Livermore National Laboratory

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本文给出了用HST/STIS获得的小间距双类星体HE 0512-3329的光学和近紫外两个分量的第一个分离光谱。特别是发射线轮廓和红移的相似性强烈表明，这个系统实际上是由同一个源的两个透镜图像组成的。假设发射线通量比不受微透镜的影响，并用来研究透镜星系引起的消光效应。经验定律的拟合表明，消光性质在两条视线上似乎是不同的。根据我们的新结果，HE 0512-3329成为少数几个显示2175 A吸收特征的河外星系之一，尽管检测只是边缘性的。然后，我们校正消光的连续通量比，以获得模场微透镜信号。由于这可能仍然受到可变性和时间延迟的影响，目前还不可能对微透镜进行详细的分析。这是第一次将微透镜效应和消光效应明确地分开。我们表明，至少在HE 0512-3329中，这两种效应都对光谱色散有显著的贡献，如果不考虑另一种效应，就不能分析其中一种效应。对于透镜建模目的，只有在对两个方面进行校正后才能使用通量比。
We present the first separate spectra of both components of the small-separation double QSO HE 0512-3329 obtained with HST/STIS in the optical and near UV. The similarities especially of the emission line profiles and redshifts strongly suggest that this system really consists of two lensed images of one and the same source. The emission line flux ratios are assumed to be unaected by microlensing and are used to study the dierential extinction eects caused by the lensing galaxy. Fits of empirical laws show that the extinction properties seem to be dierent on both lines of sight. With our new results, HE 0512-3329 becomes one of the few extragalactic systems which show the 2175 A absorption feature, although the detection is only marginal. We then correct the continuum flux ratio for extinction to obtain the dierential microlensing signal. Since this may still be significantly aected by variability and time-delay eects, no detailled analysis of the microlensing is possible at the moment. This is the first time that dierential extinction and microlensing could be separated unambiguously. We show that, at least in HE 0512-3329, both eects contribute significantly to the spectral dierences and one cannot be analysed without taking into account the other. For lens modelling purposes, the flux ratios can only be used after correcting for both eects.