Testing non-local gravity through Ultra-Diffuse Galaxies kinematics

TL;DR

This paper investigates a non-local extension of General Relativity to explain Ultra-Diffuse Galaxies' kinematics, finding that non-local corrections do not alter predictions and assessing the model's viability without dark matter.

Contribution

It demonstrates that non-local gravity models can account for galaxy kinematics without dark matter and evaluates their effects on different galaxy types.

Findings

Non-local corrections do not affect galaxy kinematic predictions.

The model can describe both dark matter lacking and dark matter dominated galaxies.

Minimum non-local radii are estimated at galaxy mass scales.

Abstract

The emergence of the Ultra-Diffuse Galaxies in recent years has posed a severe challenge to the galaxy formation models as well as the Extended Theories of Gravity. The existence of both dark matter lacking and dark matter dominated systems within the same family of astrophysical objects indeed requires the gravity models to be versatile enough to describe very different gravitational regimes. In this work, we study a non-local extension of the theory of General Relativity that has drawn increasing attention in recent years due to its capability to account for the late time cosmic acceleration without introducing any dark energy fluid. We leverage the kinematic data of three Ultra-Diffuse Galaxies: NGC 1052-DF2 and NGC 1052-DF4, which are dark matter lacking, and Dragonfly 44, which exhibits a highly dominant dark matter component. Our analysis shows that the non-local corrections to the Newtonian potential do not affect the kinematic predictions, hence no spoiling effects emerge when the Non-local Gravity model serves as a dark energy model. We additionally provide the minimum value that the characteristic non-local radii can reach at these mass scales.