Friedman–Robertson–Walker Models with Late-Time Acceleration

In order to account for the observed cosmic acceleration, a modification of the ansatz for the variation of density in Friedman–Robertson–Walker (FRW) FRW models given by Islam is proposed. The modified ansatz leads to an equation of state which corresponds to that of a variable Chaplygin gas, which in the course of evolution reduces to that of a modified generalized Chaplygin gas (MGCG) and a Chaplygin gas (CG), exhibiting late-time acceleration.