Mimetic Dark Matter

TL;DR

This paper reformulates Einstein's gravity to isolate a conformal degree of freedom, which becomes dynamical and can mimic cold dark matter, offering a new perspective on dark matter modeling.

Contribution

It introduces a covariant reformulation of gravity that makes the conformal degree of freedom dynamical and capable of mimicking dark matter.

Findings

The conformal degree of freedom is dynamical without matter.

The extra degree of freedom can mimic cold dark matter.

The equations split into traceless and trace parts, revealing new dynamics.

Abstract

We reformulate Einstein's theory of gravity, isolating the conformal degree of freedom in a covariant way. This is done by introducing a physical metric defined in terms of an auxiliary metric and a scalar field appearing through its first derivatives. The resulting equations of motion split into a traceless equation obtained through variation with respect to the auxiliary metric and an additional differential equation for the trace part. As a result the conformal degree of freedom becomes dynamical even in the absence of matter. We show that this extra degree of freedom can mimic cold dark matter.