arXiv 1801.084812018-01-25astro-ph.GA

在OGLE发现的引力透镜类星体

A Gravitationally Lensed Quasar Discovered in OGLE

Z. Kostrzewa-Rutkowska, S. Kozłowski, C. Lemon, T. Anguita, J. Greiner, M. W. Auger, Ł. Wyrzykowski, Y. Apostolovski, J. Bolmer, A. Udalski, M. K. Szymański, I.… 展开作者

Z. Kostrzewa-Rutkowska, S. Kozłowski, C. Lemon, T. Anguita, J. Greiner, M. W. Auger, Ł. Wyrzykowski, Y. Apostolovski, J. Bolmer, A. Udalski, M. K. Szymański, I. Soszyński, R. Poleski, P. Pietrukowicz, J. Skowron, P. Mróz, K. Ulaczyk, M. Pawlak

备注：: Accepted by MNRAS
DOI：: 10.1093/mnras/sty259

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摘要：

我们报告了在$\sim$ 670平方米的光学引力透镜实验（OGLE）中发现的一个新的引力透镜类星体（双重）。环绕麦哲伦星云的30度区域。该源被选为WISE的$\sim$ 60“红色W1-W2”中红外天体之一，并且对于两个（或多个）附近源，OGLE具有显著的变化量。这是引力透镜的第一次探测，其中发现是“相反的”，这意味着我们首先测量了$-132<t_{\rm AB}<-76$天（90%CL）的两个透镜类星体图像之间的时间延迟，中值为$t_{\rm AB}\approx-102$天（在观察者框架中），并且较暗的图像B落后于图像A。该系统由两个在天空中相隔1.5”的类星体图像组成，分别为$I\approx20.0$等和$I\approx19.6$等，以及一个透镜星系，在减去两个透镜图像后，在距离图像A 1.0”处可以检测到$I \approx 21.5$等源。这两个类星体的图像都显示了清晰的活动星系核宽发射线在$z=2.16$的NTT光谱。用固定源红移拟合的SED提供了透镜星系红移的估计值为$z \approx 0.9 \pm 0.2$（90% CL），而它的类型更可能是椭圆的（SED推断和透镜模型的恒星质量更可能存在于椭圆星系中）而不是螺旋的（透镜模型的首选红移）。

英文摘要：

We report the discovery of a new gravitationally lensed quasar (double) from the Optical Gravitational Lensing Experiment (OGLE) identified inside the $\sim$670 sq. deg area encompassing the Magellanic Clouds. The source was selected as one of $\sim$60 "red W1-W2" mid-IR objects from WISE and having a significant amount of variability in OGLE for both two (or more) nearby sources. This is the first detection of a gravitational lens, where the discovery is made "the other way around", meaning we first measured the time delay between the two lensed quasar images of $-132<t_{\rm AB}<-76$ days (90% CL), with the median $t_{\rm AB}\approx-102$ days (in the observer frame), and where the fainter image B lags image A. The system consists of the two quasar images separated by 1.5" on the sky, with $I\approx20.0$ mag and $I\approx19.6$ mag, respectively, and a lensing galaxy that becomes detectable as $I \approx 21.5$ mag source, 1.0" from image A, after subtracting the two lensed images. Both quasar images show clear AGN broad emission lines at $z=2.16$ in the NTT spectra. The SED fitting with the fixed source redshift provided the estimate of the lensing galaxy redshift of $z \approx 0.9 \pm 0.2$ (90% CL), while its type is more likely to be elliptical (the SED-inferred and lens-model stellar mass is more likely present in ellipticals) than spiral (preferred redshift by the lens model).

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摘要：

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