The galaxy-mass correlation and the Kilo-Degree Survey (KiDS)

在这个项目中，我们将对星系-星系透镜（GGL）进行详细的分析，这是一种研究星系质量分布以及星系和宇宙中（暗物质）物质相对分布的多功能工具。星系不会忠实地追踪潜在质量分布的分布，这一事实被称为星系偏差。要将可观测到的星系分布与从宇宙学模型中预测出来的（暗物质）分布联系起来，需要对偏差有详细的了解。偏差的大小及其对星系性质的依赖取决于星系的形成过程及其演化历史。GGL为这种偏差提供了最直接的测量方法，我们将把它作为星系类型、光度（或恒星质量）、红移以及更普遍的星系相对分布和潜在暗物质分布的函数来研究。此外，星系及其暗物质晕的径向质量分布将在大半径范围内以高统计精度进行探测。对结果的解释将在所谓的光环模型的框架内进行；结合星系的群集特性，可以推导出宇宙学参数的信息。此外，我们将研究星系和物质之间的高阶相关性。这些结果将为星系形成和演化模型提供实质性的限制，正如早期的工作所证明的那样。ESO公共调查KiDS（基度调查）为此类研究提供了独特的数据资源，因为它的天空覆盖范围，与斯隆数字巡天（SDSS）相比，它的深度更大，仪器/望远镜的卓越成像特性，以及它的波段覆盖范围。我们将在四个光学波段对1500平方度成像巡天进行全面的弱引力透镜分析。KiDS与近红外的VIKING相辅相成，在5个近红外波段覆盖相同的区域，提供准确的源目录，特别是对星系形状和光度红移的可靠估计。利用我们小组过去在数据处理、管道开发、形状和光度红移测量以及弱透镜的方法和理论发展方面的经验，我们处于一个很好的位置，可以在国际合作中发挥主导作用，在这个KiDS/VIKING调查将得到充分探索。

Within this project, we will conduct a detailed analysis of galaxy-galaxy lensing (GGL), a versatile tool to study the mass profile of galaxies and the relative distribution of galaxies and (dark) matter in the Universe. Galaxies do not faithfully trace the distribution of the underlying mass distribution, a fact called galaxy bias. A detailed knowledge of the bias is needed to be able to relate the observable galaxy distribution to the (dark) matter distribution, which is predicted from cosmological models. The magnitude of bias and its dependence on galaxy properties depends on the formation processes of galaxies and their evolutionary history. GGL provides themost direct measurement of this bias, which we will study as a function of galaxy type, luminosity (or stellar mass), redshift and,more generally, the relative distribution of galaxies and the underlying dark matter distribution. Furthermore, the radial massprofile of galaxies and their dark matter halos will be probed with high statistical accuracy out to large radii. The interpretation ofthe results will be conducted in the framework of the so-called halo model; together with the clustering properties of galaxies,information on cosmological parameters can be derived. In addition, we will study higher-order correlations between galaxies andmatter. These results will provide substantial constraints on models of galaxy formation and evolution, as demonstrated by earlier work.The ESO Public Survey KiDS (Kilo Degree Survey) provides a unique data resource for such studies, owing to its sky coverage, larger depth compared to the Sloan Digital Sky Survey (SDSS), superb imaging properties of the instrument/telescope, and its waveband coverage. We will conduct a full weak gravitational lensing analysis of the 1500 square degrees imaging survey in four optical bands. KiDS is complemented with a near-infrared counterpart VIKING, covering the same area in 5 near infrared band, to provide accurate source catalogs and, in particular, robust estimates of galaxy shapes and photometric redshifts. Capitalising on the past experience of our group in terms of data processing, pipeline development, shape and photometric redshift measurements, and methodological and theoretical developments in weak lensing, we are in an excellent position to play a leading role in an international collaboration where this KiDS/VIKING survey will be fully explored.