Galaxy cluster lensing masses in modified lensing potentials

TL;DR

This study compares galaxy cluster lensing masses in modified gravity theories to standard models, finding minimal differences at cluster centers but notable force enhancements at larger radii in the Cubic Galileon model, affecting dynamical mass tests.

Contribution

It provides the first detailed analysis of galaxy cluster lensing in Cubic Galileon and Nonlocal gravity models, assessing their impact on mass and concentration estimates.

Findings

Modified gravity models yield similar mass estimates to $ ext{Lambda}$CDM within errors.

In the Cubic Galileon model, force profiles are enhanced by 20-40% at 2-20 Mpc/h from clusters.

Screening mechanisms in the models suppress deviations within cluster radii.

Abstract

We determine the concentration-mass relation of 19 X-ray selected galaxy clusters from the CLASH survey in theories of gravity that directly modify the lensing potential. We model the clusters as NFW haloes and fit their lensing signal, in the Cubic Galileon and Nonlocal gravity models, to the lensing convergence profiles of the clusters. We discuss a number of important issues that need to be taken into account, associated with the use of nonparametric and parametric lensing methods, as well as assumptions about the background cosmology. Our results show that the concentration and mass estimates in the modified gravity models are, within the errorbars, the same as in $\Lambda$CDM. This result demonstrates that, for the Nonlocal model, the modifications to gravity are too weak at the cluster redshifts, and for the Galileon model, the screening mechanism is very efficient inside the cluster radius. However, at distances $\sim \left[2-20\right] {\rm Mpc}/h$ from the cluster center, we find that the surrounding force profiles are enhanced by $\sim20-40\%$ in the Cubic Galileon model. This has an impact on dynamical mass estimates, which means that tests of gravity based on comparisons between lensing and dynamical masses can also be applied to the Cubic Galileon model.