Determining the Relation between Dark and Luminous Matter: SDSS Weak Lensing Studies

基于N体模拟的层次结构形成模型现在提供了星系周围暗物质晕的形成、演化和成团特性的相对完整的图景。不幸的是，结构的实验测定依赖于对发光星系的观测，发光星系的形成涉及气体动力学、恒星形成和将熵反馈到星际介质中。这些过程很复杂，阻碍了直接模拟。因此，发光星系和暗物质环境之间的详细关系(“偏差”)很难确定。这种不确定性严重限制了我们将星系的宇宙学观测与理论模型进行比较的能力。该计划将对发光星系和它们的暗物质环境之间的关系进行密切协调的观测和理论研究。麦凯和他的学生将在斯隆数字天空调查中进行弱透镜测量，而埃夫拉德和韦克斯勒将在N-Body模拟中进行平行测量。这将允许在基本观测值的水平上直接比较理论和观测，而不求助于中间模型拟合。通过比较透镜测量和模拟的平行研究，这项工作将以新的方式探索偏见。

AST-0206277McKay, Timothy A.Models of hierarchical structure formation based on N-body simulations now provide a relatively complete picture of the formation, evolution, and clustering properties of darkmatter halos around galaxies. Unfortunately, experimental determination of structure relies on observations of luminous galaxies, whose formation involves gas dynamics, star formation, and the feedback of entropy into the interstellar medium. These processes are complex, hampering direct simulation. As a result, the detailed relationship between luminous galaxies and their dark matter environments (the "bias") is poorly determined.This uncertainty seriously limits our ability to compare cosmological observations of galaxies to theoretical models. This program will conduct a closely coordinated observational and theoretical study of the relationship between luminous galaxies and their dark matter environments. McKay and his students will pursue weak lensing measurements within the Sloan Digital Sky Survey, while Evrard and Wechsler will make parallel measurements within N-body simulations. This will allow direct comparison of theory and observation at the level of the fundamental observables, without recourse to intermediate model fitting. By comparing lensing measurements to parallel studies of simulations this work will probe bias in new ways.***