论文标题
第一个爱因斯坦环的红移，mg 1131+0456
A Redshift for the First Einstein Ring, MG 1131+0456
论文作者
论文摘要
Mg 1131+0456是无线电选择的重力镜头，是第一个已知的爱因斯坦环。该系统于1988年发现，由一个明亮的无线电源组成，该无线电源成像为一个环和两个紧凑的平面谱组件，分别为2.1 Arcsec。该环在光学上是微弱的（r = 23.3），陡峭地升至近红外（k = 17.8; W2 = 13.4）。在随后的几年中，该系统已经进行了深入研究，包括高分辨率无线电成像，无线电监视以及Hubble和Keck的近红外成像。晶状体星系在Z（镜头）= 0.844。但是，迄今为止，镜头源尚无光谱红移。使用档案凯克数据从1997年开始，我们报告了5438 Angstrom处的单个窄发射线的可靠检测，我们从Z（Source）= 1.849的2型Quasar与CIII I]相关联。对这种红移识别的支持来自与CIV 1549和HEII 1640相关的较弱的发射，典型的2型类星体以及档案近红外凯克光谱中缺乏发射线。我们还首次提出了Mg 1131+0456的Chandra观测周期，该观测值清楚地分解为两个点源，并结合使用〜1E-13 ERG/CM2/S，最佳拟合柱密度和〜3E22/CM2的最佳拟合柱密度。我们提出了一种新方法，通过针对具有异常高的X射线光度的源来鉴定低分辨率X射线调查（例如Erosita）的候选活性银河核，鉴于其中红外的亮度。
MG 1131+0456 is a radio-selected gravitational lens, and is the first known Einstein ring. Discovered in 1988, the system consists of a bright radio source imaged into a ring and two compact, flat-spectrum components separated by 2.1 arcsec. The ring is optically faint (R = 23.3), rising steeply into the near- and mid-infrared (K = 17.8; W2 = 13.4). The system has been intensively studied in the intervening years, including high-resolution radio imaging, radio monitoring, and near-infrared imaging with Hubble and Keck. The lensing galaxy is at z(lens) = 0.844. However, to date, no spectroscopic redshift had been reported for the lensed source. Using archival Keck data from 1997, we report the robust detection of a single narrow emission line at 5438 Angstroms, which we associate with CIII] 1909 from a type-2 quasar at z(source) = 1.849. Support for this redshift identification comes from weaker emission associated with CIV 1549 and HeII 1640, typical of type-2 quasars, as well as the lack of emission lines in archival near-infrared Keck spectroscopy. We also present, for the first time, Cycle 1 Chandra observations of MG 1131+0456, which clearly resolves into two point sources with a combined flux of ~1e-13 erg/cm2/s and a best-fit column density of ~3e22 /cm2. We suggest a new method to identify candidate lensed active galactic nuclei from low-resolution X-ray surveys such as eROSITA by targeting sources that have anomalously high X-ray luminosity given their mid-infrared luminosity.
