A classification of spherically symmetric kinematic self-similar perfect-fluid solutions

We classify all spherically symmetric spacetimes admitting a kinematic self-similar vector of the second, zeroth or infinite kind. We assume that the perfect fluid obeys either a polytropic equation of state or an equation of state of the form p = Kmu, where p and mu are the pressure and the energy density, respectively, and K is a constant. We study the cases in which the kinematic self-similar vector is not only "tilted" but also parallel or orthogonal to the fluid flow. We find that, in contrast to Newtonian gravity, the polytropic perfect-fluid solutions compatible with kinematic self-similarity are the Friedmann-Robertson-Walker solution and general static solutions. We find three new exact solutions, which we call the dynamical solutions (A) and (B) and the Lambda-cylinder solution.