Thin-shell gravastar model in f(Q, T) gravity* *SP & PKS acknowledges the National Board for Higher Mathematics (NBHM) under the Department of Atomic Energy (DAE), Govt. of India for financial support to carry out the Research project No.: 02011/3/2022 NBHM(R.P.)/R & D II/2152 Dt.14.02.2022. PKS thanks Transilvania University of Brasov for Transilvania Fellowship for Visiting Professors

Abstract

In the last few decades, gravastars have been proposed as an alternative to black holes. The stability of a gravastar has been examined in many modified theories of gravity along with Einstein's GR. The gravity, a successfully modified theory of gravity for describing the current accelerated expansion of the universe, has been used in this study to examine gravastar in different aspects. According to Mazur and Mottola [Proc. Natl. Acad. Sci. 101, 9545 (2004); Gravitational condensate stars: An alternative to black holes, I12-011, (2002)], a gravastar has three regions with three different equations of state. In this study, we examined the interior of a gravastar by considering EoS to describe the dark sector for the interior region. The next region is a thin shell of ultrarelativistic stiff fluid, in which we investigated several physical properties, including proper length, energy, entropy, and surface energy density. Additionally, we examined the surface redshift and speed of sound to check the potential stability of our proposed thin-shell gravastar model. Furthermore, we used the entropy maximization technique to verify the stability of the gravastar model. A gravastar's outer region is a complete vacuum described by exterior Schwarzschild geometry. Finally, we presented a stable gravastar model, which is singularity-free and devoid of any incompleteness in classical black hole theory.