http://arxiv.org/abs/1401.5177
The coupling between the dark sectors provides a new approach to mitigate the coincidence problem of cosmological standard model. In this paper, dark energy is treated as a fluid with a constant equation of state, whose coupling with dark matter is proportional the Hubble parameter and dark energy density, that is, $Q=3H\xi_x\rho_x$. Via combining the background energy transfer and vanishing momentum transfer potential in the frame of either dark matter or dark energy, we derive the evolution equations for the density and velocity perturbations. Using jointing data sets which include cosmic microwave background radiation, baryon acoustic oscillation, type Ia supernovae, and redshift-space distortion, we perform a full Monte Carlo Markov Chain likelihood analysis for the coupled model. The results show that information provided by $f\sigma_8(z)$ test significantly enhances the precision of the constraints on the cosmological parameters compared to the case where only geometric measurements are adopted. In particular, the mean value with errors of interaction rate is: $\xi_x=0.00354_{-0.00354-0.00354-0.00354}^{+0.000695+0.00583+0.00953}$, which means that the recently cosmic observations favored small interaction rate which is up to the order of $10^{-3}$, meanwhile, the measurement of redshift-space distortion could freeze out large interaction rate in 1$\sigma$ region.
Wed, 22 Jan 14
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