Multi-wavelength study of the gravitational lens system RXS J113155.4-123155. I. Multi-epoch optical and near infrared imaging
Multi-wavelength study of the gravitational lens system RXS J113155.4-123155. I. Multi-epoch optical and near infrared imaging
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引力透镜系统 RXS J113155.4-123155 的多波长研究。
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
J. Surdej
中科院分区：
文献类型：
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作者：
D. Sluse;J. Claeskens;B. Altieri;R. Cabanac;O. Garcet;D. Hutsemékers;C. Jean;A. Smette;J. Surdej
目标。RXS J113155.4-123155 （z = 0.66）是一个具有分辨爱因斯坦环的四重透镜类星体。本文的目标是提供这个系统的完整特征，特别是更精确的天体测量和光度测量。这些观测约束构成了透镜质量轮廓的精确测定、从时间延迟测量中推导哈勃常数H0以及对透镜星系中存在的大质量子结构的研究的强制性因素。方法。利用多台地面望远镜和HST对RXS J113155.4-123155进行了不同时期的可见光和近红外成像观测。使用MCS算法对帧进行反卷积。用奇异等温椭球(SIE) +外切变模型来模拟透镜星系的势。结果。MCS反卷积使我们能够将QSO（点状图像）的通量与其宿主星系的通量分离开来，并准确地跟踪各种滤波器中点状图像的通量变化。反卷积帧揭示了爱因斯坦环中的几个多重成像结构和透镜星系附近的一个未知物体。我们讨论了光曲线和色通量比的变化，并推断出本征变异性和微透镜效应都发生在超过一年的时间跨度内。我们证明微透镜可以很容易地解释发现论文中提出的所谓异常通量比。然而，当用SIE+剪切模拟透镜势时，观测到的通量比仍然很差。我们认为，这种分歧很难用透镜星系中子结构引起的毫透镜来解释。在第二篇论文中提出的解决方案包括一个更复杂的透镜模型，其中包括透镜引力势的八极项。
Aims. RXS J113155.4-123155 (z = 0.66) is a quadruply imaged lensed quasar with a resolved Einstein Ring. The goal of this paper is to provide a full characterization of this system, and more particularly accurate astrometry and photometry. These observational constraints constitute a mandatory ingredient for the precise determination of the lens mass profile, the derivation of the Hubble constant H0 from time delay measurements and investigations on the presence of massive substructures in the lensing galaxy. Methods. Visible and near-infrared imaging observations of RXS J113155.4-123155 were carried out at various epochs using several ground based telescopes and the HST. The frames have been deconvolved using the MCS algorithm. A Singular Isothermal Ellipsoid (SIE) + external shear has been used to model the lensing galaxy potential. Results. MCS deconvolution enables us to separate the flux of the QSO (point-like images) from that of its host galaxy and to accurately track the flux variations of the point-like images in various filters. The deconvolved frames unveil several multiply imaged structures in the Einstein ring and an unidentified object in the vicinity of the lensing galaxy. We discuss the lightcurves and the chromatic flux ratio variations and deduce that both intrinsic variability and microlensing took place during a span longer than one year. We demonstrate that microlensing may easily account for the so called anomalous flux ratios presented in the discovery paper. However, the observed flux ratios are still poorly reproduced when modeling the lens potential with a SIE+shear. We argue that this disagreement can hardly be explained by milli-lensing caused by substructures in the lensing galaxy. A solution proposed in Paper II consists in a more complex lens model including an octupole term to the lens gravitational potential.