Stable Bounded Excursion Gravastars with Regular Black Holes

This paper explores the possible existence of stable regions of bounded excursion gravastars in the background of regular black holes (Bardeen and Bardeen-de Sitter black holes). For this purpose, we match internal de Sitter geometry with an external regular black hole through an intermediate shell with an equation of state. The matter surface located at the shell greatly affects the dynamical configuration of the shell. We consider stiff and dust fluids to discuss the outcomes of the developed structures. We then determine the critical values of physical parameters at which the shell neither collapses nor expands for both cases with different choices of external and internal geometries. It is found that there does not exist any possible region of stable bounded excursion gravastar for the interior flat and exterior regular geometries. However, the stable bounded excursion gravastar is obtained for the interior de Sitter and exterior regular black holes with a suitable choice of physical parameters for both stiff and dust shells. We conclude that the possibility of the existence of both bounded excursion gravastars as well as black holes cannot be excluded in the dynamical model.