Large-scale structure challenges dilaton gravity in a 5D brane scenario with AdS bulk

TL;DR

This paper examines a 5D dilaton gravity brane model with AdS bulk and finds that it cannot support the observed large-scale structure of the universe, effectively ruling out this scenario based on current observational constraints.

Contribution

The study derives effective gravitational equations in a 5D dilaton brane model and tests its viability against large-scale structure observations, revealing its incompatibility.

Findings

Large-scale structure cannot exist in the model up to 10^4 Mpc scales.

Constraints from Newton's constant variation limit the matter density gradients.

The model is incompatible with observed universe structure.

Abstract

We study a theory of dilaton gravity in a 5-dimensional brane scenario, with a non-minimal coupling of the dilaton to the matter content of the universe localized on the brane. The effective gravitational equations at the brane are derived in the Einstein frame in the covariant approach, addressing certain misconceptions in the literature. We then investigate whether the observed large-scale structure of the universe can exist on the brane in this dilaton gravity scenario with an exact anti de Sitter bulk, assuming that the matter energy-momentum tensor has the form of an inhomogeneous perfect fluid. The corresponding constraint on the spatial derivative of the matter energy density is derived, and subsequently quantified using the current limits resulting from searches for variation of the Newton's constant. By confronting it with the observational data from galaxy surveys, we show that up to scales of the order of 10^4 Mpc, the derived bound on the spatial derivative of the matter energy density does not allow for the existence of the large-scale structure as observed today. Thus, such a dilaton gravity brane scenario is ruled out.