Disentangling dark sector models using weak lensing statistics

TL;DR

This paper investigates how weak lensing statistics can reveal signatures of coupled Dark Energy models, showing that these models affect structure formation and lensing observables in ways distinguishable from standard b4bcdm, offering a potential null test.

Contribution

It introduces a method to identify coupled Dark Energy effects through weak lensing, highlighting differences in structure growth and lensing correlations compared to b4bcdm.

Findings

Coupled Dark Energy models alter the convergence power spectrum evolution.

Weak lensing correlations vary with source redshift in coupled models.

A null test for coupled Dark Energy can be performed using lensing data.

Abstract

We perform multi-plane ray-tracing using the GLAMER gravitational lensing code within high-resolution light-cones extracted from the CoDECS simulations: a suite of cosmological runs featuring a coupling between Dark Energy and Cold Dark Matter. We show that the presence of the coupling is evident not only in the redshift evolution of the normalisation of the convergence power spectrum, but also in differences in non-linear structure formation with respect to {\Lambda}CDM. Using a tomographic approach under the assumption of a {\Lambda}CDM cosmology, we demonstrate that weak lensing measurements would result in a {\sigma}8 value that changes with the source redshift if the true underlying cosmology is a coupled Dark Energy one. This provides a generic null test for these types of models. We also find that different models of coupled Dark Energy can show either an enhanced or a suppressed correlation between convergence maps with differing source redshifts as compared to {\Lambda}CDM. This would provide a direct way to discriminate between different possible realisations of the coupled Dark Energy scenario. Finally, we discuss the impact of the coupling on several lensing observables for different source redshifts and angular scales with realistic source redshift distributions for current ground-based and future space-based lensing surveys.