# Future constraints on the gravitational slip with the mass profiles of galaxy clusters

## TL;DR

This study demonstrates that galaxy cluster mass profiles from lensing and galaxy dynamics can constrain the gravitational slip parameter to percent-level accuracy with current and future surveys, aiding tests of gravity theories.

## Contribution

It introduces a method combining lensing and dynamical data to forecast constraints on the gravitational slip parameter using galaxy clusters.

## Key findings

- Galaxy clusters can constrain the gravitational slip to percent accuracy.
- Current and future surveys can achieve these constraints with tens of clusters.
- Systematic effects have a mild impact on the constraints.

## Abstract

The gravitational slip parameter is an important discriminator between large classes of gravity theories at cosmological and astrophysical scales. In this work we use a combination of simulated information of galaxy cluster mass profiles, inferred by Strong+Weak lensing analyses and by the study of the dynamics of the cluster member galaxies, to reconstruct the gravitational slip parameter $\eta$ and predict the accuracy with which it can be constrained with current and future galaxy cluster surveys. Performing a full-likelihood statistical analysis, we show that galaxy cluster observations can constrain $\eta$ down to the percent level already with a few tens of clusters. We discuss the significance of possible systematics, and show that the cluster masses and numbers of galaxy members used to reconstruct the dynamics mass profile have a mild effect on the predicted constraints.