Dark Energy: A Unifying View

Understand

Different models of the cosmic substratum which pretend to describe the present stage of accelerated expansion of the Universe like the $\Lambda$CDM model or a Chaplygin gas, can be seen as special realizations of a holographic dark energy cosmology if the option of an interaction between pressurless dark matter and dark energy is taken seriously.

• The corresponding interaction strength parameter plays the role of a cosmological constant.
• Differences occur at the perturbative level.
• In particular, the pressure perturbations are intrinsically non-adiabatic.