Multi-wavelength studies of the luminous and dark mass profiles of galaxy-clusters in wide-field imaging surveys

在最近确定了基本宇宙学常数之后，深刻理解宇宙中暗物质和发光物质的分布是现代宇宙学的关键问题之一。因此，星系团提供了明确的实验室环境，以研究在广泛的物质和星系密度范围内的质量分布和星系演化。今天的广视场成像相机提供了一个独特的机会来获取大的和在统计学上非常好理解的星系团样本，只根据它们的质量属性进行选择，使用它们在微弱(背景)星系形状上的弱引力透镜印记。根据目前的提议，我们要求延长一个旨在利用这些独特的未来数据集的项目的资金。将在已有的多色数据集上选择银河星系团，将对指向长XMM曝光的深部多色图像进行联合剪切和X射线选择，并将对各种星系团选择技术的效率进行比较。不同选择的星系团中的星系群将被比较；特别是，我们将调查剪切选择的星系团是否具有特别高的质量与光比，这将揭示经典的星系团选择方法中的偏差。此外，我们将致力于与WFI数据的数据简化和分析有关的几个技术方面的工作，特别是用于不均匀照明和PSF校正的新方法；这些技术问题是充分利用未来调查数据的关键步骤，远远超出弱透镜应用的范围。

After the recent determination of the fundamental cosmological constants, a profound understanding of the dark and luminous matter distribution in the Universe is one of the key problems in modern cosmology. Hereby, clusters of galaxies provide well-defined laboratory environments to study the mass distribution and galaxy evolution over wide ranges of matter and galaxy densities. Today’s wide-field imaging cameras offer a unique opportunity to obtain large and statistically very well understood samples of clusters, with a selection based solely on their mass properties, using their weak gravitational lensing imprint on the shape of faint (background) galaxies. With the current proposal we ask for an extension of funding for a project aiming at exploiting these unique future data sets. Galaxy clusters will be selected on already available multi-colour data sets, a joint shear- and X-ray selection will be performed on deep multi-colour images pointing towards long XMM exposures, and a comparison of the efficiency of various cluster selection techniques will be performed. The galaxy population in the differently selected clusters will be compared; in particular, we will investigate whether shear-selected clusters have a particularly high mass-to-light ratio which would reveal a bias in ‘classical’ cluster selection methods. In addition, we will work on several technical aspects related to the data reduction and analysis of WFI data, in particular new methods for the inhomogeneous illumination and PSF corrections; these technical issues are an essential step for the full exploitation of future survey data, well beyond weak lensing applications.