Splashback in galaxy clusters as a probe of cosmic expansion and gravity

TL;DR

This paper investigates how the splashback radius in galaxy clusters can serve as a probe for cosmic expansion and gravity theories, revealing observable signatures of modified gravity models through analytical and simulation studies.

Contribution

It introduces a detailed analysis of splashback in modified gravity models, highlighting differences from ΛCDM and potential observational signatures in galaxy cluster outskirts.

Findings

Significant differences in splashback location between modified gravity and ΛCDM.

Observable signatures in splashback due to transition from screened to unscreened regions.

Interplay between dynamical friction and gravity affecting splashback behavior.

Abstract

The splashback radius is a physical scale in dark matter halos that is set by the gravitational dynamics of recently accreted shells. We use analytical models and N-body simulations to study the dependence of splashback on dark energy and screened modified gravity theories. In modified gravity models, the transition from screened to unscreened regions typically occurs in the cluster outskirts, suggesting potentially observable signatures in the splashback feature. We investigate the location of splashback in both chameleon and Vainshtein screened models and find significant differences compared with $\Lambda$CDM predictions. We also find an interesting interplay between dynamical friction and modified gravity, providing a distinctive signature for modified gravity models in the behavior of the splashback feature as a function of galaxy luminosity.