Modified gravity approach based on a preferred time foliation

TL;DR

This paper introduces a relativistic modified gravity model based on a preferred time foliation, aiming to explain galactic phenomena without dark matter, and recovers MOND phenomenology in the non-relativistic limit.

Contribution

It presents a new relativistic gravity model using a scalar field called the Khronon, which reproduces MOND behavior and modifies gravitational lensing predictions.

Findings

Recovers MOND phenomenology in the non-relativistic limit

Predicts gravitational lensing similar to general relativity

Provides an alternative to dark matter at galactic scales

Abstract

We propose, in a heuristic way, a relativistic modified gravity model as an alternative to particle dark matter at galactic scales. The model is based on a postulated preferred time foliation described by a dynamical scalar field called the "Khronon". In coordinates adapted to the foliation it appears as a modification of general relativity violating local Lorentz invariance in a regime of weak gravitational fields. The model is a particular case of non-canonical Einstein-aether theory, but in which the aether vector field is hypersurface orthogonal. We show that this model recovers the phenomenology of the modified Newtonian dynamics (MOND) in the non-relativistic limit, and predicts the same gravitational lensing as general relativity but with a modified Poisson-type potential.