Mimicking dark matter in Horndeski gravity

TL;DR

This paper investigates whether a specific sector of Horndeski gravity can mimic cold dark matter and explain galactic rotation curves, proposing a multi-scalar field approach with minimal assumptions.

Contribution

It demonstrates the potential for a sector of Horndeski gravity to replicate dark matter effects at cosmological and galactic scales using multiple scalar fields.

Findings

Possible to mimic cold dark matter with scalar fields

Can explain galactic rotation curve flattening

Requires at least two scalar fields

Abstract

Since the rediscovery of Horndeski gravity, a lot of work has been devoted to the exploration of its properties, especially in the context of dark energy. However, one sector of this theory, namely the one containing the coupling of the Einstein tensor to the kinetic term of the scalar field, shows some surprising features in the construction of black holes and neutron stars. Motivated by these new results, I explore the possibility that this sector of Horndeski gravity can mimic cold dark matter at cosmological level and also explain the flattening of galactic rotation curves. I will show that, in principle, it is possible to achieve both goals with at least two scalar fields and a minimal set of assumptions.