论文标题
了解观察到的低质量星系簇的大型推断的爱因斯坦半径
Understanding the large inferred Einstein radii of observed low-mass galaxy clusters
论文作者
论文摘要
我们评估了一个主张，即观察到的质量〜10^14 mSUN的星系簇比LCDM中预测的更为集中。我们产生模拟的强力透镜观测值，从宇宙学水动力学模拟中获取透镜，并以与真实宇宙相同的方式进行分析。观察到的和模拟的镜头弧相互一致，三个主要影响造成了先前声称的不一致。首先，包含重型物质的星系簇的中心密度高于仅使用暗物质模拟的对应物。其次，由于存在明显的重力透镜弧而选择的簇样品优先找到具有大爱因斯坦半径的集中浓缩簇。第三，镜头弧通常比临界曲线更直，并且所选的图像分析方法（通过弧线拟合圆）高估了爱因斯坦半径。在考虑了这三个效果之后，LCDM预测星系簇应产生与观察到的宇宙中的巨型镜头弧相匹配的巨型镜头弧。
We assess a claim that observed galaxy clusters with mass ~10^14 Msun are more centrally concentrated than predicted in LCDM. We generate mock strong gravitational lensing observations, taking the lenses from a cosmological hydrodynamical simulation, and analyse them in the same way as the real Universe. The observed and simulated lensing arcs are consistent with one another, with three main effects responsible for the previously claimed inconsistency. First, galaxy clusters containing baryonic matter have higher central densities than their counterparts simulated with only dark matter. Second, a sample of clusters selected because of the presence of pronounced gravitational lensing arcs preferentially finds centrally concentrated clusters with large Einstein radii. Third, lensed arcs are usually straighter than critical curves, and the chosen image analysis method (fitting circles through the arcs) overestimates the Einstein radii. After accounting for these three effects, LCDM predicts that galaxy clusters should produce giant lensing arcs that match those in the observed Universe.
