Universal relations for bosonic stars

Abstract

This thesis studies different types of compact objects in General Relativity, focusing on universality in scalar and vector boson stars, including Proca and Proca-Higgs stars, as well as mixed boson-fermion systems. The goal is to understand their universal behavior, potential applications, and observational characteristics important for astrophysics and gravitational wave studies. The research looks at both nonrotating and rotating versions of these stars, using mass-radius and mass-frequency curves to explain their properties. It covers neutron stars, scalar and vector boson stars, and mixed neutron-scalar boson stars, with a focus on new solutions, especially for rotating stars. The study uses mathematical techniques like multipolar expansion to analyze the structure and properties of these stars, adapting methods such as Geroch-Hansen’s.