Accelerated expansion through interaction

Zimdahl, Winfried
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Interactions between dark matter and dark energy with a given equation of state are known to modify the cosmic dynamics. On the other hand, the strength of these interactions is subject to strong observational constraints. Here we discuss a model in which the transition from decelerated to accelerated expansion of the Universe arises as a pure interaction phenomenon. Various cosmological scenarios that describe a present stage of accelerated expansion, like the LCDM model or a (generalized) Chaplygin gas, follow as special cases for different interaction rates. This unifying view on the homogeneous and isotropic background level is accompanied by a non-adiabatic perturbation dynamics which can be seen as a consequence of a fluctuating interaction rate.
Comment: 4 pages, to appear in the Proceedings of the Spanish Relativity Meeting ERE2008 in Salamanca, September 2008
Astrophysics, General Relativity and Quantum Cosmology, High Energy Physics - Theory