Explorations of Boson Stars

Abstract

Boson stars are configurations of the gravitating complex scalar field in the Einstein’s GeneralTheory of Relativity that have many applications in astrophysics and beyond. In this thesis we explore several boson stars models both in regular asymptotically flat spacetime and AdS space. In the asymptotically flat spacetime we explore the solitonic boson star model. The solitonic boson stars look like thin shells that interpolate between different scalar field vacua which allows them to become very compact and have unusual physical properties. At the same time finding the most compact of such stars poses a significant numerical challenge. To overcome this challenge we develop a novel Chebyshev collocation multidomain code and use it to investigate both rotating and non- rotating boson stars in the regime where scalar field profiles of these stars are very stiff. In AdS space we investigate boson stars coupled to a U(1) gauge field and demonstrate their connection to the scar states originally discovered in condensed matter theory.