Boson Stars in General Scalar-Tensor Gravitation: Equilibrium Configurations

TL;DR

This paper investigates equilibrium configurations of boson stars within general scalar-tensor theories of gravitation, analyzing their mass ranges, formation during cosmic evolution, and effects of varying gravitational coupling.

Contribution

It introduces a comprehensive analysis of boson stars in scalar-tensor theories, including different couplings and their impact on star properties and formation scenarios.

Findings

Boson star masses are comparable to those in general relativity.

Masses are sensitive to variations in the effective gravitational constant.

Significant radial variations in coupling can affect star structure.

Abstract

We study equilibrium configurations of boson stars in the framework of general scalar-tensor theories of gravitation. We analyse several possible couplings, with acceptable weak field limit and, when known, nucleosynthesis bounds, in order to work in the cosmologically more realistic cases of this kind of theories. We found that for general scalar-tensor gravitation, the range of masses boson stars might have is comparable with the general relativistic case. We also analyse the possible formation of boson stars along different eras of cosmic evolution, allowing for the effective gravitational constant far out form the star to deviate from its current value. In these cases, we found that the boson stars masses are sensitive to this kind of variations, within a typical few percent. We also study cases in which the coupling is implicitly defined, through the dependence on the radial coordinate, allowing it to have significant variations in the radius of the structure.