Phantom behavior via cosmological creation of particles

TL;DR

This paper proposes that the observed phantom-like dark energy behavior could be explained by quantum vacuum effects and particle production, rather than exotic fields violating energy conditions.

Contribution

It introduces a novel interpretation of dark energy's equation of state as an effective value arising from quantum vacuum and particle creation effects.

Findings

Models are consistent with recent observational data.

Particle production can mimic phantom dark energy behavior.

Provides an alternative to fields violating energy conditions.

Abstract

Recent determinations of the equation of state of dark energy hint that this may well be of the phantom type, i.e., $w_{de} < -1$. If confirmed by future experiments, this would strongly point to the existence of fields that violate the dominant energy condition, which are known to present serious theoretical difficulties. This paper presents an alternative to this possibility, namely, that the measured equation of state, $w_{de}$, is in reality an effective one, the equation of state of the quantum vacuum, $w_{\Lambda} = -1$, plus the negative equation of state, $w_{c}$, associated to the production of particles by the gravitational field acting on the vacuum. To illustrate this, three phenomenological models are proposed and constrained with recent observational data.