Scalar quasinormal modes of gravastars

In this work, we present a detailed investigation of gravastars within the framework of scalar-tensor theories, emphasizing both the background and perturbed levels for trivial and non trivial scalar field. We derive and analyze the background equations governing the equilibrium configurations of gravastars by considering the interaction between matter and scalar field through a conformal transformation. By selecting two forms of the coupling function, we identify distinct physical characteristic that leads to deviations from predictions made by general relativity. We show that that the scalar field has a considerable influence on the compactness parameter. By extending our study to the perturbed level, we show also that quasinormal modes are considerably impacted by the presence of scalar field. New and interesting solutions are found, which are absent in general relativity.