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Barotropic Frw Cosmologies With Chiellini Damping In Comoving Time, Haret C. Rosu, S.C. Mancas, Pisin Chen
Barotropic Frw Cosmologies With Chiellini Damping In Comoving Time, Haret C. Rosu, S.C. Mancas, Pisin Chen
Publications
For nonzero cosmological constant Λ, we show that the barotropic FRW cosmologies as worked out in the comoving time lead in the radiation-dominated case to scale factors of identical form as for the Chiellini dissipative scale factors in conformal time obtained recently by us in Phys. Lett. A 379, 882 (2015). This is due to the Ermakov equation which is obtained in this case. For zero cosmological constant, several textbook solutions are easily obtained as particular cases of our formulas and hypergeometric solutions are also reminded.
Barotropic Frw Cosmologies With Chiellini Damping, Haret C. Rosu, S.C. Mancas, Pisin Chen
Barotropic Frw Cosmologies With Chiellini Damping, Haret C. Rosu, S.C. Mancas, Pisin Chen
Publications
It is known that barotropic FRW equations written in the conformal time variable can be reduced to simple linear equations for an exponential function involving the conformal Hubble rate. Here, we show that an interesting class of barotropic universes can be obtained in the linear limit of a special type of nonlinear dissipative Ermakov–Pinney equations with the nonlinear dissipation built from Chiellini's integrability condition. These cosmologies, which evolutionary are similar to the standard ones, correspond to barotropic fluids with adiabatic indices rescaled by a particular factor and have amplitudes of the scale factors inverse proportional to the adiabatic index.