STRONG GRAVITATIONAL LENSING MODELLING OF GALAXY CLUSTERS IN THE ERA OF BIG DATA

Current observational facilities and surveys are revolutionizing the field of strong lensing (SL) by galaxy clusters. Remarkably, the Euclid Survey will cover approximately 15,000 square degrees of the sky, detecting SL features in thousands of massive clusters. Complementarily, the James Webb Space Telescope (JWST) is providing extremely deep and high-resolution observations, revealing a number of multiple images and substructures greater than previously unknown, and thus enabling lens models of unprecedented accuracy. The synergy between these observatories will drastically improve the number of currently known SL systems and significantly enhance the quality of SL studies. In order to deal with large sets of galaxy clusters and/or characterized by a huge number of observables, a modeling code capable of reconciling speed and accuracy is mandatory. The SL parametric modeling code Gravity.jl addresses this challenge directly, having been specifically developed for cluster-scale lensing analyses. Its high-performance architecture makes it ideally suited for processing the large and complex datasets from these and next-generation observatories. In this Thesis, we present the SL Gravity.jl-based study of the galaxy cluster Abell 2390 combining, for the first time, Euclid ERO imaging and archival MUSE spectroscopy. Gravity.jl's computational efficiency enabled comparison of over 10 distinct total mass parameterizations within approximately just two hours per model. We then further explore what future SL studies of galaxy clusters based on Euclid imaging will look like by investigating how the expected limited number of identifiable multiple images affects the measurements of the lens parameters and of other quantities of interest, such as the cluster total mass. Finally, we push the limits of SL analyses by presenting the study of the galaxy cluster MACS J0416, an interesting complex system for which recent JWST observations have helped in the identification of nearly 500 spectroscopically-confirmed multiple images – the highest number ever recorded for a galaxy cluster. We will present the preliminary results of the first fully multi-plane lensing studies of this system carried on with Gravity.jl.