Cosmological attractors in massive gravity

TL;DR

This paper explores Lorentz-violating massive gravity models that can naturally lead to cosmic acceleration through an attractor mechanism, with potential implications for understanding dark energy.

Contribution

It introduces a class of Lorentz-violating massive gravity models with an attractor solution that explains cosmic acceleration without dark energy.

Findings

The Newtonian potential includes a confining term in linear approximation.

The Universe evolves towards an attractor point with enhanced symmetry.

The attractor can produce cosmic acceleration in certain parameter ranges.

Abstract

We study Lorentz-violating models of massive gravity which preserve rotations and are invariant under time-dependent shifts of the spatial coordinates. In the linear approximation the Newtonian potential in these models has an extra ``confining'' term proportional to the distance from the source. We argue that during cosmological expansion the Universe may be driven to an attractor point with larger symmetry which includes particular simultaneous dilatations of time and space coordinates. The confining term in the potential vanishes as one approaches the attractor. In the vicinity of the attractor the extra contribution is present in the Friedmann equation which, in a certain range of parameters, gives rise to the cosmic acceleration.