Weak Gravitational Lensing

宇宙微波背景(CMB)是大爆炸后38万年的残余辐射。通过测量温度和光的偏振的各向异性涨落，可以高精度地推断宇宙学参数。然而，CMB光子并不是沿着直线路径到达我们的望远镜，而是因为暗物质结构沿视线引起的时空扭曲而扭曲它们的路径--这种效应被称为弱透镜。这是从最近的普朗克卫星上测量到的，具有非常高的意义。除了CMB光子被弱透镜外，来自星系的可见光光子也被弱透镜。通过测量来自星系的微弱透镜，我们希望能够提取关于暗能量的信息，在MSSL，我们在将于2020年发射的新的欧空局宇宙学卫星欧几里德中发挥主导作用，以测量这种影响。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。由于这两组数据都包含微弱的透镜信息，因此这项任务将导致对星系和早期宇宙的详细了解。首先，这个项目将为这项工作建立理论框架(在这里报道的研究的基础上)，然后将其应用于星系和CMB信息的模拟，最后将其应用于来自ESO KIDDS调查和ACT实验的最先进的星系和CMB弱透镜数据。[待确认，待MPHIL完成]

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]