Large-scale stability and astronomical constraints for coupled dark-energy models

Abstract

The physics of the dark energy and the dark matter is still an open issue in cosmology. The dark energy occupies about 68.5% of the total energy density of the universe today [1], and is believed to accelerate its observed expansion, but the physical nature, origin, and time evolution of this dark energy remain unknown. On the other hand, the dark matter sector (occupying almost 27.5% of the total energy density of the present-day universe) appears to be the principal gravitational in uence on the formation of large-scale structure in the universe and its existence is supported by direct evidence from the spiral galaxy rotation curves and cluster dynamics [2]. At present, we have a many dark-energy models [3, 4] and, according to syntheses of all the current observational data, -cosmology appears to be the simplest cosmological model that can explain the bulk of the evidence. However, the unexplained numerical value of the cosmological constant, and the coincidences between the present densities of the di erent dark and luminous components of the universe, provoke us to search for new cosmological scenarios in which the observed state of a airs is more natural. In this work we will explore cosmologies where dark energy interacts and exchanges energy with dark matter.