Probing Vainsthein-screening gravity with galaxy clusters using internal kinematics and strong and weak lensing

We use high-precision combined strong/weak lensing and kinematics measurements of the total mass profiles of the observed galaxy clusters MACS J1206.2-0847 and Abell S1063, to constrain the relativistic sector of the general DHOST dark energy theories, which exhibit a partial breaking of the so called Vainsthein screening mechanism, on the linear level of scalar fluctuations around a cosmological background. In particular, by using the MG-MAMMPOSSt framework developed in Pizzuti et al., for the kinematics analysis of member galaxies in clusters, along with lensing mass profile reconstructions, we provide new constraints on the coupling Y2 that governs the theory's relativistic contribution to the lensing potential. The new bound from the combination of kinematics and lensing measurements of MACS 1206, Y2=-0.12+0.66-0.67 at 2σ, provides about a two-fold improvement on previous constraints. In the case of Abell S1063, a >2σ tension with the GR expectation arises. We discuss this in some detail, and we investigate the possible sources of systematics that can explain the tension. We further discuss why the combination of kinematics of member galaxies with lensing is capable of providing much tighter bounds compared to kinematics or lensing alone, and we explain how the number density profile of tracers, as well as the choice of the velocity anisotropy profile, affects the final results.