Weak Gravitational Lensing

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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]