Relevant Papers

Cosmic Microwave Background

The picture on the left shows a map of fluctuations in the cosmic microwave background (CMB) as measured by the Planck satellite. The red and blue spots are hot and cold patches of CMB radiation in different regions of the sky. These fluctuations are tiny in size, typically one part in a hundred thousand, and sit on top of an average CMB radiation field having a temperature of about 3 degree Kelvin. The radiation was emitted when the Universe was extremely young, only a few hundred thousand years after the Big Bang (compare that to its current age, about 14 billion years). It was around this time that the Universe had expanded and cooled sufficiently to allow the formation of atoms for the first time, which was accompanied by the emission of vast amounts of radiation, observed today as the CMB. The fluctuations are a direct snapshot of the physical conditions of the Universe at this time, depicting acoustic waves in a plasma quickly becoming neutral through the recombination of protons and electrons to form neutral Hydrogen.

I am interested in how maps of the CMB temperature and polarisation fluctuations can be used to learn about physical conditions in the early and late Universe, in particular through the secondary scattering of CMB photons in galaxy clusters and the effects of gravitational lensing on the CMB. I use a range of theoretical and statistical methods to improve our modelling and data analysis techniques.