Hybrid dark energy

TL;DR

This paper investigates a hybrid dark energy model involving a scalar field that transitions from freezing to thawing behavior, potentially reconciling observational data with theoretical constraints in cosmology.

Contribution

It introduces a novel hybrid quintessence scenario where the scalar field's equation of state evolves from freezing to thawing, addressing observational and theoretical challenges.

Findings

The scalar field approaches -1 today, indicating accelerated expansion.

The universe will eventually decelerate eternally due to the scalar field dynamics.

The hybrid model may reconcile observational preferences with string theory constraints.

Abstract

Extending previous results [Phys. Rev. Lett. 97, 081301 (2006)], we explore the cosmological implications of a new quintessence scenario driven by a slow rolling homogeneous scalar field whose equation of state behaved as freezing over the entire cosmic evolution, is approaching -1 today, but will become thawing in the near future, thereby driving the Universe to an eternal deceleration. We argue that such a mixed behavior, named \emph{hybrid}, may reconcile the slight preference of current observational data for freezing potentials with the impossibility of defining observables in the String/M-theory context due to the existence of a cosmological event horizon in asymptotically de Sitter universes as, e.g., pure freezing scenarios.