Abstract

As the most massive gravitationally bound structures in the Universe, galaxy clusters frequently act as strong gravitational lenses. Strong lensing (SL) enables us to reconstruct the total mass distribution of a cluster with extreme accuracy, providing insights into the physical properties of dark matter and its interplay with baryons. SL models are also crucial for studying magnified high-redshift sources and measuring cosmological parameters from observed time delays between lensed variable sources. However, the accuracy of SL models is limited by parametric degeneracy, which hinders the reconstruction of the mass distribution of cluster members. This degeneracy can be resolved using independent information from their stellar kinematics. After a general introduction to SL by galaxy clusters, I will present how we leveraged deep MUSE /VLT observations of SL clusters to build a large catalogue of accurate stellar velocity dispersion measurements of early-type member galaxies. These measurements serve as the foundation for calibrating new scaling relations that describe their structure in a set of highly accurate SL models and for comparisons with cosmological hydrodynamical simulations of galaxy clusters, aimed at testing the ΛCDM paradigm.