Key Probes of the Extreme Universe: Accretion Discs, Gravitational Waves, CMB and Galaxy Surveys

This grant proposal seeks to advance the understanding of astrophysical discs, the analysis of gravitational waves, and the science exploitation of the CMB and galaxy surveys in order to open new windows on the structure of the Universe. The following are summaries of our proposed projects: 1. Discs of gas are found around young stars (where planets form) and around black holes in the centres of galaxies. This project will investigate the behaviour and appearance of discs in which the orbital motion is elliptical or misaligned, causing the gas to be squeezed repeatedly. 2. Planets form from the gas and dust swirling around newly born young stars, a complicated multi-faceted process that is still poorly understood. This project investigates how turbulence, magnetic fields, and jets influence planet formation in the inner regions of these disks. 3. Many objects in the Universe accrete gas that orbits around them. This project will study accretion onto objects with a material surface, such as white dwarfs, young stars and planets, when the gas must pass through the so-called boundary layer which is still poorly understood. 4. The detection of gravitational waves by LIGO in 2015 has opened up unprecedented opportunities for the exploration of the Universe. From black holes to the enigmatic dark matter and cosmological expansion, we will develop machine learning methods to explore new facets of the world we live in. 5. Building on our world-leading Planck satellite pipeline to measure deviations from Gaussian ("bell-curve") statistics, we will implement extended versions for new data from the cosmic microwave sky (Simons Observatory (SO)), as well as galaxy surveys (Dark Energy Survey (DES)), while also looking for the expected correlations between them. The results will yield non-linear clustering parameters, the tightest constraints on primordial non-Gaussianity and critical tests for inflationary models. 6. Cosmological observations offer us the unique opportunity to probe high-energy physics and the quantum regime of gravity during the first fraction of a second of the Big Bang. Breakthroughs in understanding the consequences of fundamental principles of physics in cosmology have very recently led to new exciting predictions of non-Gaussian statistics which we here confront with large cosmological datasets, specifically from the cosmic microwave sky (Simons Observatory). 7. In this project, we will make new measurements of the lensing of the cosmic microwave background, the gravitational deflection of relic light from the Big Bang, using 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 unknown mass of neutrino particles.