PhD defence: A Perturbative Perspective on Cosmological Large-Scale Structure

PLEASE NOTE: The candidate gives a layman's talk, therefore the livestream will start fifteen minutes earlier.

With the advent of modern telescopes, it has become possible to survey huge portions of the night sky and thereby studying the evolution of the Universe. Astronomers collect the coordinates and shapes of tens or even hundreds of millions of galaxies far outside our own galaxy, the Milky Way. The light from these galaxies has travelled up to several billions of years to arrive here on Earth. For reference, the light coming from the Sun takes only a few minutes to arrive here. Hence, by looking at distant galaxies we can chart the history of the Universe across cosmic time.

Under the influence of gravity, these galaxies arrange themselves in web-like patterns and their shapes are distorted through tidal interactions, much like the Moon squashes the Earth and causes tides at sea. By studying these patterns or ‘large-scale structure’ in more detail using more advanced models, we can look for answers to ultimate questions, such as ‘Where did we come from?’ and ‘How will the Universe develop further?’ 

In this thesis, I have developed and implemented several new tools that will allow the research community to analyse large-scale structure in ever more detail than before. In particular, I have devised more accurate and more precise models for the correlations between shapes of galaxies and shown that they outperform already existing approaches. I have also introduced new numerical tools that increase the speed of existing calculations by several orders of magnitude. These tools can be used for ongoing surveys such as Euclid, the Dark Energy Spectroscopic Instrument (DESI) and the Legacy Survey of Space and Time (LSST). In the coming ten years, we will learn more than ever about the nature of gravity and the laws of physics during epochs long before the existence of mankind and telescopes.