Improved strong lensing modelling of galaxy clusters using the Fundamental Plane: the case of Abell S1063

Giovanni Granata, Amata Mercurio, Claudio Grillo, Luca Tortorelli, Pietro Bergamini, Massimo Meneghetti, Piero Rosati, Gabriel Bartosch Caminha, Mario Nonino

Abstract

The usual choice of adopting simple power-law scaling relations to link the total mass of members with their luminosity is one of the possible inherent systematics within strong lensing (SL) models of galaxy clusters, and therefore on the derived cluster masses.
I will present how we use the Fundamental Plane (FP) relation to obtain more accurate and complex relations between the observables describing cluster members, and to completely fix their mass from their observed magnitudes and effective radii.
Using new information on their structural parameters (from HST imaging) and kinematics (from MUSE data), we build the FP for the early-type galaxies of the cluster Abell S1063. We take advantage of the calibrated FP to develop an improved SL model of the total mass of the cluster core.
The new method allows for a reduction of the uncertainty on the value of the core radius of the main DM halo by more than 30% with respect to the previous work. We also find a different relation between the mass and the velocity dispersion of members, which shows a significant scatter.
Thanks to a new estimate of the stellar mass of cluster members from HST data, we measure the two-dimensional, cumulative mass profiles out to a radius of 350 kpc, for all baryonic and dark matter components of the cluster. Finally, I will present a comparison between the physical properties of sub-halo in our model and those predicted by high-resolution hydrodynamical simulations. We find
good agreement in terms of stellar mass fraction, and some discrepancies in terms of sub-halo compactness.