Revealing the structure of the universe: Gravitational waves, cosmology and exoplanets

This is an ambitious proposal to advance our understanding of the structures in our Universe, exploiting the latest STFC observational programmes in gravitational waves, the cosmic microwave background, galaxy surveys and exoplanets. Our main goals are: 1. We will investigate the statistics of matter in the Universe using the latest galaxy survey data (the Dark Energy Survey), as well as maps of the cosmic microwave background, the relic radiation left over from the Big Bang. Determining whether these statistics are Gaussian (obey the normal distribution), we will be able to better understand gravitational collapse and to look for primordial signals from the early Universe, testing theories for the origin of galaxies. 2. In this project, we will develop new approaches to the study of CMB lensing, the gravitational deflection of relic light from the Big Bang, and apply them to the state-of-the-art Simons Observatory experiment. With our novel methods for extracting and inverting the lensing deflection, we will provide a clearer view of the beginning of the universe and the distribution of dark matter. 3. The spatial distribution of everything on cosmological distances, from atoms to light, from energy to spacetime itself was set up in the first fraction of a second after the big bang, in an era called inflation. By studying models of inflation, we will predict specific patterns of regularity in this apparently haphazard distribution and search for evidence of this signal in the Cosmic Microwave Background. 4. One of the most spectacular discoveries from astrophysics and cosmology is that most of the Universe's matter content is dark, i.e. invisible in electromagnetic observations. The 2017 Nobel-Prize winning detection of gravitational waves now provides us with a new channel to search for the enigmatic dark matter. For this purpose we will compute how dark matter environments manifest themselves in the gravitational wave signal from black hole binaries. 5. The recent direct detection of gravitational waves emitted in black hole mergers provides an unprecedented opportunity to test Einstein's General Relativity (GR) for strong gravitational fields. To do this we need theoretical predictions for how a deviation from GR would affect the gravitational waves emitted in a black hole merger. We will develop the mathematics needed to perform supercomputer simulations of black hole mergers in a very broad class of theories. It will use these to identify how the predictions of such theories differ from those of GR in the strong gravity regime. 6. Discoveries of the gravitational wave sources by LIGO/Virgo observatory necessitate the need to understand the origin of the objects that produce them - binary black holes and neutron stars. This project takes a fresh look at the dynamical evolution of such relativistic binaries in dense stellar clusters to understand their contribution to LIGO/Virgo discoveries. 7. We will study the breaking of tidal waves in stars caused by close exoplanets, to understand the rates at which their orbits are shrinking. We will also provide the scientific community with efficient codes to compute tidal dissipation in rotating and evolving stars and giant planets, so that the origins and orbital evolution of many observed exoplanet systems can be understood. 8. Planets are born in the disks of gas and dust encircling very young stars. These disks are both turbulent and magnetised; we will seek, via computer simulations, how these two processes influence the formation of planets, and the evolution of the disks that bear them. 9. We have embarked on a joint outreach venture with the Discovery Channel to reach a very large international audience through the launch of a new multimedia Video on Demand service. It will use content we supply from our gravitation and cosmology research projects, on which we will also base our talks and websites for the public and schools.