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Multi-scale connectivity and hierarchical topology of the cosmic web

PhD ceremony:Mr G. (Georg) Wilding
When:November 15, 2022
Supervisors:prof. dr. M.A.M. (Rien) van de Weijgaert, prof. dr. G. (Gert) Vegter
Co-supervisor:dr. K. Efstathiou
Where:Academy building RUG
Faculty:Science and Engineering
Multi-scale connectivity and hierarchical topology of the cosmic

Where does the Universe come from, what is it made of, and how will it evolve in the future? These are just a few questions the study of cosmology wants to answer. In this thesis, I contribute to this field by studying how topological data analysis (TDA) can be used to describe and analyse the large-scale structure of the Universe. This structure forms a cosmic web, where galaxies and matter trace long, thin strands, which join at small nodes, and are surrounded by empty voids. In my thesis, I deal with challenges both from the perspective of cosmology, as well as mathematics. I want to understand the formation of structure, how its web-like connections can be described mathematically, and what information about the Universe we can deduce from this analysis.

Our current understanding is that the Universe mostly consists of dark matter and dark energy. We know that both of these phenomena have a profound impact on the evolution of the Universe. However, their exact composition is as of yet unknown. Different and competing theories about the nature of dark matter and dark energy have been formulated. In this thesis, I apply TDA to study the evolution of cosmic connections under different theories.

Using computer simulations, I investigate what pattern we can expect according to our current understanding, but also how these patterns would change if dark energy behaved differently. I prepare for studying patterns in the real Universe by examining how the mass of dark matter that surrounds a galaxy (its halo) influences their place in the cosmic web.