Relativistic stars in a cubic Galileon Universe

TL;DR

This paper investigates relativistic stars within a cubic Galileon model that evades gravitational wave constraints, demonstrating that the Vainshtein mechanism suppresses deviations from General Relativity inside stars but not beyond the Vainshtein radius.

Contribution

It derives scalar field profiles for relativistic stars in a cubic Galileon framework, showing how the Vainshtein mechanism affects stellar structure and scalar field behavior.

Findings

Stellar structure matches General Relativity inside the Vainshtein radius.

Scalar field is not suppressed beyond the Vainshtein radius.

Solutions include an additional integration constant besides mass.

Abstract

We study relativistic stars in Hordenski theories that evade the gravitational wave constraints and exhibit the Vainshtein mechanism, focusing on a model based on the cubic Galileon Lagrangian. We derive the scalar field profile for static spherically symmetric objects in asymptotically de Sitter space-time with a linear time dependence. The exterior solution matches to the black hole solution found in the literature. Due to the Vainshtein mechanism, the stellar structure is indistinguishable from that of General Relativity with the same central density as long as the radius of the star is shorter than the Vainshtein radius. On the other hand, the scalar field is not suppressed beyond the Vainshtein radius. These solutions have an additional integration constant in addition to the mass of the star.