Probing the Type 3 interacting dark-energy model using matter pairwise velocity

TL;DR

This study uses N-body simulations to investigate how Type 3 dark sector interaction models, involving momentum exchange between dark matter and dark energy, affect large-scale structure velocity statistics.

Contribution

It demonstrates the impact of the momentum exchange coupling and scalar field potential slope on matter velocity statistics, highlighting their degeneracy and potential as probes.

Findings

Effects of $eta$ and $\lambda$ on velocity are degenerate.

Velocity statistics can probe dark sector interactions.

Disentangling $eta$ and $\lambda$ is crucial for cosmological analysis.

Abstract

Dark sector interactions can be explored via the so-called Type 3 model where dark matter and dark energy exchange momentum only, so as to minimize deviations from the $\Lambda$CDM background expansion history. Using N-body simulations, we analyze the imprint of Type 3 model parameters, the momentum exchange coupling constant $\beta$ and the slope of scalar field potential $\lambda$, on large-scale structure observables, particularly the matter pairwise velocity statistics. We find that the effects of $\beta$ ($<0$) and $\lambda$ on the mean matter peculiar pairwise velocity and velocity dispersion are degenerate. Our results highlight the potential of velocity statistics as a probe of dark sector interactions and underscore the importance of disentangling $\beta$ and $\lambda$ in cosmological analyses.