Observational constraints on interactions between dark energy and dark matter with momentum and energy transfers

TL;DR

This paper constrains a dark energy model with coupled dark matter through momentum and energy exchanges, using observational data to explore effects on structure growth and the CMB, and finds evidence for non-zero momentum transfer.

Contribution

It introduces observational constraints on a coupled dark energy model with both momentum and energy exchanges, highlighting the potential to resolve cosmological tensions.

Findings

Positive momentum coupling suppresses low-redshift structure growth.

Negative energy coupling influences the sound horizon at CMB decoupling.

Data favor non-zero momentum exchange with a peak at negative energy transfer.

Abstract

We place observational constraints on a dark energy (DE) model in which a quintessence scalar field $\phi$ is coupled to dark matter (DM) through momentum and energy exchanges.The momentum transfer is weighed by an interaction between the field derivative and DM four velocity with a coupling constant $\beta$, whereas the energy exchange is characterized by an exponential scalar-field coupling to the DM density with a coupling constant $Q$. A positive coupling $\beta$ leads to the suppression for the growth of DM density perturbations at low redshifts, whose property offers a possibility for resolving the $\sigma_8$ tension problem. A negative coupling $Q$ gives rise to a $\phi$-matter-dominated epoch, whose presence can reduce the sound horizon around the Cosmic Microwave Background (CMB) decoupling epoch. Using the data of Planck 2018, 12-th Sloan Digital Sky Survey, Phantheon supernovae samples, and 1-year dark energy survey, we find that the two couplings are constrained to be $\beta=0.332^{+1.246}_{-0.237}$ and $Q =-0.0312^{+0.0312}_{-0.0085}$ at 68\,\% confidence level (CL). Thus, there is an interesting observational signature of the momentum exchange ($\beta \neq 0$) between DE and DM, with a peak of the probability distribution of the energy transfer coupling at $Q<0$.