Interaction Between Dark Energy And Dark Matter In The Cosmic Microwave Background Radiation

Based on the astronomy observations, it is clear that our universe is under accelerating expansion. To explain the accelerating expansion, peo-ple assumes that there is another component in the universe called "dark energy". Dark energy and dark matter dominate the universe today. In theory, dark energy and dark matter can couple to each other. In this work, we studied two possible forms of the interaction. First, we generalized the cosmological model in which energy transfers between dark matter and dark energy to model with time-dependent dark energy equation of state. Then we proposed an interaction model analogous to Thomson scattering, in which dark matter particles scatter off dark energy. We examine the stabilities in perturbation formalism of both models. We explored the impact of the in-teractions on the cosmic microwave background and the degeneracy among coupling between dark sectors, dark energy equation of state and matter abundance. Finally, we try to break the degeneracy by doing global fitting using complementary observational data sets and get the constraint on the interaction between dark sectors for both models.