Study of dark interactions through strong gravitational lenses

TL;DR

This study investigates models of dark matter and dark energy interactions using strong gravitational lensing data, revealing significant interaction strengths and earlier cosmic acceleration than standard models.

Contribution

It introduces a novel analysis of sign-changeable interaction models constrained by strong lensing data, highlighting their potential to test dark sector interactions.

Findings

Interaction strength $eta$ is negative across models.

Strong lensing indicates earlier cosmic acceleration ($z_t extasciitilde 1.8-2.1$).

Constraints are larger in magnitude than previous supernovae, CMB, and BAO results.

Abstract

The possible interaction between the dark components of the Universe (dark matter and dark energy) stands as an attractive alternative to the standard $\Lambda$CDM cosmological model. In this work, we present a novel analysis of three sign-changeable interaction models whose coupling term $Q$ depends explicitly on the deceleration parameter $q$ and is proportional to different energy densities: dark matter, dark energy, and total energy density. To constrain these models, we combine strong gravitational lensing data on two complementary scales: a sample of early-type galaxies acting as lenses and the galaxy cluster Abell 1689. Our results show that the interaction strength $\beta$ depends on the choice of the coupling term $Q$, with all models yielding negative values of $\beta$, indicative of a dark interaction scenario. The $\beta$ values obtained in this work are significantly larger in magnitude than those previously reported using Type Ia supernovae, CMB, and BAO. The strong-lensing constraints indicate a transition to cosmic acceleration at earlier redshifts ($z_t \sim 1.8-2.1$) than that predicted by the $\Lambda$CDM model, while remaining consistent with cosmic chronometer measurements within the reconstructed confidence regions. Therefore, our study shows that strong gravitational lensing data provide an independent and competitive cosmological probe capable of testing interacting dark energy scenarios. The sensitivity of lensing observables to the expansion history enables access to complementary information about dark-sector dynamics beyond standard cosmological probes.