Flat rotation curves using scalar-tensor theories

TL;DR

This paper demonstrates that scalar-tensor theories in the weak field limit can produce flat galaxy rotation curves, determining dark matter distribution and scalar field potential, with analytical density profiles matching NFW cuspy profiles.

Contribution

It introduces a method to derive dark matter density profiles from scalar-tensor theories that fit observed flat rotation curves in galaxies.

Findings

Scalar-tensor theories can produce flat rotation curves.

Derived density profiles are as cuspy as NFW profiles.

Analytical results depend on fundamental parameters (, ).

Abstract

We computed flat rotation curves from scalar-tensor theories in their weak field limit. Our model, by construction, fits a flat rotation profile for velocities of stars. As a result, the form of the scalar field potential and DM distribution in a galaxy are determined. By taking into account the constraints for the fundamental parameters of the theory $(\lambda, \alpha)$, it is possible to obtain analytical results for the density profiles. For positive and negative values of $\alpha$, the DM matter profile is as cuspy as NFW's.