An high-precision strong lensing model of the galaxy cluster PSZ1 G311.65-18.48

Strong gravitational lensing is one of the best performing methods to study the mass distribution in the central regions of galaxy clusters. The progress witnessed recently on the lens modeling techniques was made possible by the several observational programs conducted with the Hubble Space Telescope (HST) and complemented by spectroscopic observations of a relatively large number of massive galaxy clusters. In this work we use a new method to combine lensing and galaxy kinematics measurements to conduct a strong lensing analysis of the cluster PSZ1 G311.65-18.48, with the aim of constructing a parametric lens model of the mass distribution in its core. We use HST observations conducted in several bands, complemented with VLT/MUSE spectroscopic observations. The multiple image and cluster member catalogues are the main ingredients required for the construction of a parametric lens model with the software Lenstool. Throughout this thesis we describe the process that led to the construction of the cluster final model, which evolved through several intermediate steps where the model complexity increased progressively. The aim was to recover the mass distribution which minimizes the differences between observed and model-predicted multiple image positions. Our resulting reference model is the first lens model for this galaxy cluster ever published and reproduces the observed multiple images with very high accuracy. It can be used for several applications, including the characterization of the source producing the famous Sunburst Arc, or predicting the re-appearance of the possible transient source recently reported by Vanzella et al. (2020).