Scalar quasinormal modes of gravastars

In this study, we present a detailed investigation of gravastars within the framework of scalar-tensor theories, emphasizing both the background and perturbed levels for trivial and nontrivial scalar field. We derive the background equations that govern the equilibrium configurations of gravastars by examining the interaction between matter and the scalar field through a conformal transformation. By selecting two forms of the coupling function, we identify distinct physical characteristics that lead to deviations from the predictions made by general relativity. Our findings indicate that the scalar field significantly influences the compactness parameter. By extending our study to the perturbed level, we demonstrate that quasinormal modes are considerably affected by the presence of the scalar field. We discover new and intriguing quasinormal modes that are absent in general relativity.