Revisiting metric perturbations in tensor-vector-scalar theory

TL;DR

This paper analyzes cosmological scalar perturbations in TeVeS theory, highlighting the role of the vector field in enhancing structure formation and characterizing perturbation evolution across different scales.

Contribution

It provides a semi-analytic framework for studying scalar perturbations in TeVeS, emphasizing the vector field's role in structure growth during matter domination.

Findings

Vector field is crucial for boosting structure growth.

Perturbation evolution is characterized on sub- and superhorizon scales.

Scalar modes are expressed in a form suitable for modified gravity analysis.

Abstract

I revisit cosmological perturbations in Bekenstein's tensor-vector-scalar theory (TeVeS). Considering only scalar modes in the conformal Newtonian gauge, the extra degrees of freedom are expressed in a way suitable for studying modifications at the level of the metric potentials. Assuming a universe in the matter-dominated phase, I discuss the mechanism responsible for boosting structure growth, and confirm the vector field as its key ingredient. Using a semi-analytic approach, I further characterize the evolution of density perturbations and the potentials on sub- and superhorizon scales.