Abstract:
The general exact solution of the Einstein-matter field equations
describing spherically symmetric shells satisfying an equation of
state in closed form is discussed under general assumptions of physical
reasonableness. The solutions split into two classes: a class of “astrophysically
interesting” solutions describing “ordinary” matter with positive
density and pressure, and a class of “phantom-like” solutions with
positive density but negative active gravitational mass, which can also
be of interest in several “very strong fields” regimes. Known results on
linear-barotropic equations of state are recovered as particular cases.