Dynamical evolution of boson stars in Brans-Dicke theory

Abstract

We study the dynamics of a self-gravitating scalar field solitonic object (boson star) in the Jordan-Brans-Dicke (BD) theory of gravity. We show dynamical processes of this system such as (i) black hole formation of a perturbed equilibrium configuration on an unstable branch, (ii) migration of a perturbed equilibrium configuration from an unstable branch to a stable branch, and (iii) the transition from an excited state to a ground state. We find that the dynamical behavior of boson stars in BD theory is quite similar to that in general relativity (GR), with comparable scalar wave emission. We also demonstrate the formation of a stable boson star from a Gaussian scalar field packet with flat gravitational scalar field initial data. This suggests that boson stars can be formed in the BD theory in much the same way as in GR.