Gaugessence: a dark energy model with early time radiation-like equation of state

TL;DR

This paper introduces a quintessence dark energy model based on non-Abelian gauge fields that behave like dark radiation in early times and transition to dark energy at late times, explaining the universe's acceleration.

Contribution

It presents a novel late-time cosmological model where gauge fields track radiation and evolve into dark energy, with robust early dark radiation predictions affecting $N_{eff}$.

Findings

Dark radiation component contributes to $N_{eff}$

Model exhibits tracking behavior leading to a common evolutionary trajectory

Predicts early dark radiation as a robust feature

Abstract

In this work, we study a new quintessence model associated with non-Abelian gauge fields, minimally coupled to Einstein gravity. This gauge theory has been recently introduced and studied as an inflationary model, called gauge-flation. Here, however, we are interested in the late time cosmology of the model in the presence of matter and radiation to explain the present time accelerating Universe. During the radiation and matter eras, the gauge field tracks radiation and basically acts like a dark radiation sector. As we approach lower redshifts, the dark component takes the form of a dark energy source which eventually becomes the dominate part of the energy budget of the Universe. Due to the tracking feature of our model, solutions with different initial values are attracted to a common trajectory. The existence of early dark radiation is a robust prediction of our model which contributes to the effective number of relativistic species, $N_{\rm eff}$ and has its own interesting observational features.