Boson stars in biscalar extensions of Horndeski gravity

TL;DR

This paper constructs and analyzes boson star solutions within biscalar Horndeski gravity, exploring effects of nonminimal kinetic couplings and self-interactions, revealing new properties compared to standard models.

Contribution

It introduces boson star solutions in biscalar Horndeski gravity with nonminimal kinetic couplings and self-interactions, extending previous models with novel potential structures.

Findings

Solutions differ from standard minimally coupled models

Self-interactions lead to degenerate vacua

Nonminimal coupling affects boson star properties

Abstract

This paper is concerned with the construction and analysis of boson stars in the context of nonminimal derivative coupling theories. In particular we embed our model in the biscalar extension of Horndeski gravity, considering a scalar field theory displaying a nonminimally coupled kinetic term given by the Einstein tensor. We focus on the case where the potential is given by a mass term only, and when a six order self-interaction is included. In the latter case we consider specific couplings in the self-interacting terms in such a way that our self-interaction is given by a positive definite potential presenting two degenerate local vacua. We show how solutions can be obtained and we compare its principal properties with standard configurations constructed with the usual minimally coupled kinetic term.