Weak Gravitational Lensing

宇宙微波背景辐射（CMB）是宇宙大爆炸后38万年的残余辐射。通过测量这种光的温度和偏振的各向异性波动，可以高精度地推断出宇宙参数。然而，CMB的光子并没有沿着一条直线到达我们的望远镜，相反，它们的路径被暗物质结构沿着视线引起的时空扭曲所扭曲，这种效应被称为弱透镜效应。最近的普朗克卫星测量到了这一点，具有非常重要的意义。和宇宙微波背景的光子一样，来自星系的可见光光子也是弱透镜。通过测量来自星系的弱透镜效应，我们希望能够提取有关暗能量的信息，在MSSL，我们在新的欧几里得宇宙学卫星中发挥主导作用，该卫星将于2020年发射，以测量这种效应。该博士项目将开发以最佳方式结合普朗克数据和欧几里德数据的工具。由于这两个数据集都包含弱透镜信息，因此这项任务将导致对这两个星系和早期宇宙的详细了解。最初，该项目将为这项工作开发理论框架（建立在这里报道的研究基础上https://lateuniverse.wordpress.com/2014/09/29/combining-information-over-13-billion-years-of-time/），然后将其应用于星系和CMB信息的模拟，最后将其应用于ESO KiDS调查和ACT实验中最先进的星系和CMB弱透镜数据。[待确认，以完成哲学硕士课程为准]

The cosmic microwave background (CMB) is the remnant radiation from 380,000 years after the big bang. By measuring the anisotropic fluctuations in the temperature and polarisation of this light cosmological parameters can be inferred to high accuracy. However the CMB photons do not follow a straight path to our telescopes, but instead their paths are distorted by the warping of spacetime caused by dark matter structures along the line of sight - an effect known as weak lensing. This has been measured with very high significance from the recent Planck satellite. As well as CMB photons being weakly lensed the visible light photons from galaxies are also weak lensed. By measuring the weak lensing from galaxies we hope that information on dark energy can be extracted, and at MSSL we play a leading role in the new ESA cosmology satellite called Euclid that will launch in 2020 to measure this effect. This PhD project will develop the tools to combine Planck data with Euclid data in an optimal way. Because both data sets contain weak lensing information this is a task that will result detailed understanding of both galaxies and the early Universe. Initially this project will develop the theoretical framework for this work (building upon the study reported here https://lateuniverse.wordpress.com/2014/09/29/combining-information-over-13-billion-years-of-time/), then apply this to simulations of the galaxy and CMB information, and finally apply this to the state-of-the-art galaxy and CMB weak lensing data from the ESO KiDS survey and ACT experiments. [To be confirmed, subject to completion of MPhil]