2008/03/07 by Mauricio Cataldo, Patricio Mella, P. Minning +2
Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #hep-th
paper · pdf · doi:10.1016/j.physletb.2008.03.022
published as Phys.Lett.B662:314-322,2008 · 10 pages. Accepted for publication in Physics Letters B
arxiv created 2008/03/07 · openalex publication_date 2008/03/15 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We provide a detailed description for power-law scaling Friedmann–Robertson–Walker cosmological scenarios dominated by two interacting perfect fluid components during the expansion. As a consequence of the mutual interaction between the two fluids, neither component is conserved separately and the energy densities are proportional to 1/t2. It is shown that in flat FRW cosmological models there can exist interacting superpositions of two perfect fluids (each of them having a positive energy density) which accelerate the expansion of the universe. In this family there also exist flat power-law cosmological scenarios where one of the fluids may have a “cosmological constant” or “vacuum energy” equation of state (p=−ρ) interacting with the other component; this scenario exactly mimics the behavior of the standard flat Friedmann solution for a single fluid with a barotropic equation of state. These possibilities of combining interacting perfect fluids do not exist for the non-interacting mixtures of two perfect cosmic fluids, where the general solution for the scale factor is not described by power-law expressions and has a more complicated behavior. In this study is considered also the associated single fluid model interpretation for the interaction between two fluids.