Novel Gravastar Solutions: Investigating Stability, Energy, and Entropy in the Presence of Cloud of Strings and Quintessence

Abstract: Gravastars, theoretical alternatives to black holes, have captured the interest of scientists in astrophysics due to their unique properties. This paper aims to further investigate the exact solution of a novel gravastar model based on the Mazur-Mottola (2004) method within the framework of general relativity, specifically by incorporating the cloud of strings and quintessence. By analyzing the gravitational field and energy density of gravastars, valuable insights into the nature of compact objects in the universe can be gained. Understanding the stability of gravastars is also crucial for our comprehension of black holes and alternative compact objects. For this purpose, we present the Einstein field equations with the modified matter source and calculate the exact solutions for the inner and intermediate regions of gravastars. The exterior region is considered as a black hole surrounded by the cloud of strings and quintessence, and the spacetimes are matched using the Darmoise-Israel formalism. {An investigation is conducted on the stability of gravastars using linearized radial perturbation. Additionally, the proper length, energy content, and entropy of the shell are computed. The stability of gravastars is positively correlated with the enhancement of the cloud of strings parameter, while it is negatively correlated with the growth in the quintessence field parameter.} The paper concludes with a summary of the findings and their implications in the field of astrophysics and cosmology.