PhD ceremony Ms. E. Russell: Analytical exploration of large scale structure

PhD ceremony: Ms. E. Russell, 12.45 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: Analytical exploration of large scale structure

Promotor(s): prof. M.A.M. van de Weijgaert

Faculty: Mathematics and Natural Sciences

This thesis focuses on two different problems of modern cosmology. Today, it is known that the Universe is well represented by the Friedman-Robertson- Walker model, which describes it as being homogeneous and isotropic on large scales. However, the structure formation of the Universe shows complex weblike structure formation called the Cosmic Web on small scales. It is believed that the Cosmic Web is formed by tiny anisotropy fluctuations that are observed in the Cosmic Microwave Background (CMB).

In Chapter 2 we progress from this fact and investigate the possibility of Universe models that are initially anisotropic and asymptotically Friedman Robertson Walker cosmologies. These initially anisotropic models may provide a possible framework to describe the origin of the CMB anisotropies and hence the Cosmic Web. Voids fill 95% of the observable volume of the Cosmic Web, so evolution of voids in the present day Universe is one of the key issues of modern cosmology, and knowledge of this is required to understand the dynamical evolution of the present day Universe. The hierarchical evolution of voids is the subject of the second goal of this thesis.

In Chapter 3 we give the necessary explanations and formulations of void evolution. In Chapter 4, a void merging tree algorithm of spherical growing voids is presented. In Chapter 5, a more complex void merging algorithm is constructed by considering the environmental effects on voids, leading to collapse and merging behaviors in the Universe. These two void merging models represent the first void merging algorithms to date.