CASUS Institute Seminar, Dr. Ezgi Yilmaz, Center for Advanced Systems Understanding CASUS at Helmholtz-Zentrum Dresden-Rossendorf (HZDR)

Ezgi holds a PhD in engineering physics. Her interests cover relativity, gravitation and cosmology. Ezgi’s work focuses on the large-scale structure of the universe and, in particular, on the search of a general relativistic scheme appropriate for formulating structure formation at all scales. Ezgi joined CASUS in early 2023.

Abstract of the talk // Linear perturbation theory and Newtonian N-body simulations are the two conventional tools crucial to the study of structure formation in the universe, addressing the early- and late-enough stages of evolution, respectively. Based on General Relativity, the former approach very successfully describes linear deviations from the homogeneous background at large scales. However, towards the formation of galaxies, clusters and eventually the cosmic web, as nonlinear collapse takes place in sufficiently small regions, one inevitably resorts to numerical methods in order to track the growth of density contrasts. Modelling gravitational collapse via Newtonian approximation here has the evident drawback that the scheme lacks relativistic corrections essential to cosmological processes. Additionally, it is inappropriate for considering any relativistic species or any models alternative to concordance cosmology.

The recently proposed cosmic screening approach addresses this problem and provides a self-consistent formulation of cosmological perturbations compatible with both limits. At the nonlinear scale, it complies with Newtonian behavior and on the opposite end, close enough to the horizon, it introduces a cutoff scale for gravitational interactions in favor of the cosmological principle. In this seminar Ezgi will explore this approach in detail, focusing on its implementations in cosmological simulations together with a comparative analysis with the default relativistic scheme of the publicly available N-body code gevolution.

Ezgi will be talking live in Görlitz. However, as the event is organized in a hybrid format that includes a videoconferencing tool by Zoom Inc., people interested in the topic have the chance to also join the talk remotely. Please ask for the login details via