Dinamic model of spherical perturbations in Friedmann Universe
  A selfconsistent system of equations describing evolution of linear spherically symmetric perturbations in Fridmann world by an arbitrary equation of state is obtained. The perturbations singular part corresponding to massive particle-like source is extracted, an evolutionary equation for mass of this source is obtained and exactly solved. An exact solution of evolutionary equations of state for perturbations by an arbitrary equation of state is constructed. 
Yu.G. Ignatyev, N. Elmakhi
gr-qc math-ph math.MP