论文标题
所有美好的事物都以三分：镜头镜头PKS1830-211的第三张图像
All good things come in threes: the third image of the lensed quasar PKS1830-211
论文作者
论文摘要
强烈的引力镜片扭曲了我们对宇宙学距离的来源的看法，但对前景对象的质量含量以及宇宙的几何形状和特性带来了宝贵的约束。我们报告了第三个连续源的检测到高动态范围和高角度分辨率的ALMA多频观测中，对强透明的类星体PKS1830-211进行了检测。第三个源是点状的，略微位于对角线的北部，与图像B相连的两个主透镜图像A和B，0.3 Arcsec远离图像B。它的通量密度比图像A和B弱约140倍，并且具有类似的频谱索引，与同步器发射兼容。我们得出的结论是，该来源很可能是预期的高度脱落的类星体图像。此外，我们首次在毫米波长下检测到与图像A和B相对应的弱和不对称延伸，这与在厘米波长处看到的爱因斯坦环的最亮区。它们的光谱指数比紧凑型图像A，B和C的陡峭指数表明它们是由类星体的不同组成部分引起的。使用Gravlens代码，我们探讨了我们发现对镜头模型的含义，并提出了一个简单的模型，该模型可以准确地重现我们的ALMA数据和先前的VLA观察结果。通过对图像A和B之间的时间延迟进行更精确，准确的测量，系统PKS1830-211可以帮助将哈勃常数限制为几个百分之几的精度。
Strong gravitational lensing distorts our view of sources at cosmological distances but brings invaluable constraints on the mass content of foreground objects and on the geometry and properties of the Universe. We report the detection of a third continuum source toward the strongly lensed quasar PKS1830-211 in ALMA multi-frequency observations of high dynamic range and high angular resolution. This third source is point-like and located slightly to the north of the diagonal joining the two main lensed images, A and B, 0.3 arcsec away from image B. It has a flux density that is ~140 times weaker than images A and B and a similar spectral index, compatible with synchrotron emission. We conclude that this source is most likely the expected highly de-magnified third lensed image of the quasar. In addition, we detect, for the first time at millimeter wavelengths, weak and asymmetrical extensions departing from images A and B that correspond to the brightest regions of the Einstein ring seen at centimeter wavelengths. Their spectral index is steeper than that of compact images A, B, and C, which suggests that they arise from a different component of the quasar. Using the GravLens code, we explore the implications of our findings on the lensing model and propose a simple model that accurately reproduces our ALMA data and previous VLA observations. With a more precise and accurate measurement of the time delay between images A and B, the system PKS1830-211 could help to constrain the Hubble constant to a precision of a few percent.
