Dynamics of entropy perturbations in assisted dark energy with mixed kinetic terms

Understand

We study dynamics of entropy perturbations in the two-field assisted dark energy model.

• Based on the scenario of assisted dark energy, in which one scalar field is subdominant compared with the other in the early epoch, we show that the entropy perturbations in this two-field system tend to be constant on large scales in the early epoch and hence survive until the present era for a generic evolution of both fields during the radiation and matter eras.
• This behaviour of the entropy perturbations is preserved even when the fields are coupled via kinetic interaction.
• Since, for assisted dark energy, the subdominant field in the early epoch becomes dominant at late time, the entropy perturbations can significantly influence the dynamics of density perturbations in the universe.