2006/04/30 by John D. Barrow, Timothy Clifton, T. Clifton · 13 citations
Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #astro-ph #gr-qc
paper · pdf · doi:10.1103/physrevd.73.103520
published as Phys.Rev.D73:103520,2006 · 12 pages, 1 figure
arxiv created 2006/05/25 · openalex publication_date 2006/05/30 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We provide a simple mathematical description of the exchange of energy between two fluids in an expanding Friedmann universe with zero spatial curvature. The evolution can be reduced to a single nonlinear differential equation which we solve in physically relevant cases and provide an analysis of all the possible evolutions. Particular power-law solutions exist for the expansion scale factor and are attractors at late times under particular conditions. We show how a number of problems studied in the literature, such as cosmological vacuum-energy decay, particle annihilation, and the evolution of a population of evaporating black holes, correspond to simple particular cases of our model. In all cases we can determine the effects of the energy transfer on the expansion scale factor. We also consider the situation in the presence of ``antidecaying'' fluids and so-called ``phantom'' fluids which violate the dominant energy conditions.