Future CMB cosmological constraints in a dark coupled universe

TL;DR

Future CMB satellite missions like EPIC can significantly improve constraints on cosmological parameters, but their effectiveness is reduced if dark energy and dark matter are coupled, unless CMB lensing is utilized.

Contribution

This paper demonstrates how dark sector coupling affects the precision of cosmological parameter constraints from future CMB observations.

Findings

Dark coupling increases errors on key parameters

CMB lensing extraction improves constraints

Future missions can still constrain coupled dark energy models

Abstract

Cosmic Microwave Background satellite missions as the on-going Planck experiment are expected to provide the strongest constraints on a wide set of cosmological parameters. Those constraints, however, could be weakened when the assumption of a cosmological constant as the dark energy component is removed. Here we show that it will indeed be the case when there exists a coupling among the dark energy and the dark matter fluids. In particular, the expected errors on key parameters as the cold dark matter density and the angular diameter distance at decoupling are significantly larger when a dark coupling is introduced. We show that it will be the case also for future satellite missions as EPIC, unless CMB lensing extraction is performed.