Testing non-local gravity by clusters of galaxies

TL;DR

This paper investigates non-local gravity theories at galaxy cluster scales, comparing theoretical predictions with gravitational lensing data, and finds they are consistent with observations similarly to General Relativity, providing new constraints on model parameters.

Contribution

It introduces a scalar-tensor non-local gravity model, tests it against galaxy cluster lensing data, and derives constraints on non-local parameters, advancing understanding of non-local gravity's viability.

Findings

Non-local gravity models agree with lensing data at cluster scales.

Constraints on Navarro-Frenk-White parameters were obtained.

Lower bounds for non-local length scales were established.

Abstract

Extended theories of gravity have been extensively investigated during the last thirty years, aiming at fixing infrared and ultraviolet shortcomings of General Relativity and of the associated $\Lambda$CDM cosmological model. Recently, non-local theories of gravity have drawn increasing attention due to their potential to ameliorate both the ultraviolet and infrared behavior of gravitational interaction. In particular, Integral Kernel theories of Gravity provide a viable mechanism to explain the late time cosmic acceleration so as to avoid the introduction of any form of unknown dark energy. On the other hand, these models represent a natural link towards quantum gravity. Here, we study a scalar-tensor equivalent model of General Relativity corrected with non-local terms, where corrections are selected by the existence of Noether symmetries. After performing the weak field limit and generalizing the results to extended mass distributions, we analyse the non-local model at galaxy cluster scales, by comparing the theoretical predictions with gravitational lensing observations from the CLASH program. We obtain agreement with data at the same level of statistical significance as General Relativity. We also provide constraints for the Navarro--Frenk--White parameters and lower bounds for the non-local length scales. The results are finally compared with those from the literature.