Evolution of Dark Matter with Weak Gravitational Lensing

AST-0236702伯恩斯坦，加里M.宇宙被认为主要由暗物质组成，一些未知的物质，只有通过其引力效应才能知道它的存在。在这些效应中，有一种是星光的偏转，也被称为引力透镜效应：当光线穿过暗物质时，在暗物质聚集体后面看到的物体的外观会被扭曲。在某些情况下，这种透镜扭曲是戏剧性的，但我们对宇宙中几乎每个星系的看法都被干预暗物质扭曲到非常小的程度。通过测量这些微弱的引力透镜效应，人们可以绘制暗物质的分布图。这种扭曲通常相当于背景星系的1%伸长，因此利用弱引力透镜需要天文学家测量100，000到10，000，000个星系的形状，并仔细注意可以模仿引力透镜的轻微光学缺陷。然而，回报是巨大的，因为“看到”暗物质的能力可以回答许多关于宇宙的最重要的问题。这项资助下的工作将应用新技术来分析弱透镜数据，并利用深透镜调查和其他大型成像调查收集的数据将这些测量的精度提高到百分之几的水平。有了这些数据，就有可能绘制出自红移0.5以来星系周围暗物质晕的演化。其他现有的和新的数据将被分析，以绘制大质量星系团中的暗物质。

AST-0236702Bernstein, Gary M.The Universe is believed to consist primarily of dark matter, some unknown substance that makes its presence known only by its gravitational effects. Among these effects is the deflection of starlight, also known as gravitational lensing: objects seen behind a dark matter concentration will have their appearance distorted as the light rays pass the dark matter. In some cases this lensing distortion is dramatic, but our view of nearly every galaxy in the Universe is distorted to a very small degree by intervening dark matter. By measuring these weak gravitational lensing effects, one can map the distribution of the dark matter. The distortion typically amounts to a 1% elongation of a background galaxy, so exploitation of weak gravitational lensing requires the astronomer to measure 100,000 to 10,000,000 galaxy shapes, and to pay careful attention to slight optical defects that can mimic gravitational lensing. The rewards are great, however, since the ability to "see" dark matter can answer many of the most important questions about the Universe. The work under this grant will apply new techniques to the analysis of weak lensing data, and advance the precision of these measurements to the few-percent level using data being gathered by the Deep Lens Survey and other large imaging surveys. With these data it will be possible to plot the evolution of dark matter halos around galaxies since redshift 0.5. Other existing and new data will be analyzed to map the dark matter in massive galaxy clusters.***