Density Perturbation Growth in Teleparallel Cosmology

TL;DR

This paper investigates how cosmological perturbations evolve in teleparallel dark energy models with a scalar field, revealing differences from general relativity and enhanced gravitational interactions during tracker phases.

Contribution

It provides the first detailed analysis of perturbation growth in teleparallel dark energy, highlighting differences from standard cosmology despite similar degrees of freedom.

Findings

Perturbation evolution differs from general relativity across all scales.

Gravitational interactions are enhanced during tracker evolutions.

Number of propagating degrees of freedom matches quintessence models.

Abstract

We study the cosmological perturbations in teleparallel dark energy models in which there is a dynamical scalar field with a non-minimal coupling to gravity. We find that the propagating degrees of freedom are the same as in quintessence cosmology despite that variables of the perturbed vierbein field are greater than those in metric theories. We numerically show some evident discrepancy from general relativity in the evolutions of the perturbations on all scales of the universe. We also demonstrate that the gravitational interactions are enhanced during the unique tracker evolutions in these models.