Relativistic formulation and physical viability of anisotropic analytic gravastars

Abstract We develop a fully consistent anisotropic extension of the Imran class ICG (Isotropic Compact Gravastar) model within general relativity. A geometry-coupled anisotropy is introduced at the exact equation level, ensuring regularity at the center, smooth matching to the exterior Schwarzschild spacetime, and the absence of thin shells. A controlled option enforces vanishing anisotropy at both the center and the surface. The resulting equilibrium configurations satisfy energy conditions, causality, compactness bounds, and stability diagnostics. The admissible mass–radius domain overlaps that of neutron star like compact objects, and the isotropic ICG solution is recovered smoothly in the zero-anisotropy limit. These results provide a robust anisotropic gravastar background for future rotational and tidal analyses.