David Grüber
FCUP / IA

Abstract
In this talk, I will provide an overview of the work conducted during my PhD on the theoretical, numerical, and observational aspects of domain walls in cosmology. After a concise review of the formation of walls and their cosmological evolution, I will present how we established and optimized field theory simulations of domain wall networks, which ultimately led us to introduce a novel method to extract root-mean-square wall velocities from such simulations. I will subsequently highlight the most important results we obtained on various topics related to cosmic domain walls, including the exploration of the parameter-free velocity-dependent one-scale model as well as non-standard scenarios, like the interaction with compact objects. For the remainder of the presentation, I will introduce a new semi-analytical framework we developed to describe the emission of a Stochastic Gravitational Wave Background by scaling wall networks. This simple, effective model can be used to estimate the fractional contribution of gravitational waves from domain walls to the cosmic budget with minimal assumptions and, moreover, provides us with insights into the full spectral shape of this background. I will then conclude by demonstrating how we can apply this framework to inform us about the contribution of domain walls to the gravitational wave background recently detected by Pulsar Timing Arrays.

2025 May 07, 13:30

IA/U.Porto
Centro de Astrofísica da Universidade do Porto (Classroom)
Rua das Estrelas, 4150-762 Porto