The imprint of the interaction between dark sectors in large scale cosmic microwave background anisotropies

TL;DR

This paper investigates how interactions between dark energy and dark matter affect large-scale cosmic microwave background anisotropies, proposing methods to detect such interactions and constraining their strength with observational data.

Contribution

It provides a detailed analysis of perturbation equations for interacting dark sectors and demonstrates how CMB data can constrain the coupling, addressing the cosmic coincidence problem.

Findings

Large scale CMB anisotropies are sensitive to dark sector interactions.

Cross-correlation of CMB with large scale structure can detect coupling.

Constrained coupling values can solve the coincidence problem within 1σ.

Abstract

Dark energy interacting with dark matter is a promising model to solve the cosmic coincidence problem. We study the signature of such interaction on large scale cosmic microwave background (CMB) temperature anisotropies. Based on the detail analysis in perturbation equations of dark energy and dark matter when they are in interaction, we find that the large scale CMB, especially the late Integrated Sachs Wolfe effect, is a useful tool to measure the coupling between dark sectors. We also discuss the possibility to detect the coupling by cross-correlating CMB maps with tracers of the large scale structure. We finally perform the global fitting to constrain the coupling by using the CMB power spectrum data together with other observational data. We find that in the $1\sigma$ range, the constrained coupling between dark sectors can solve the coincidence problem.