Quantum fields near phantom-energy `sudden' singularities

TL;DR

This paper investigates the behavior of quantum fields near future phantom-energy singularities, analyzing how different quantum vacuum states influence the singularity's strength and the universe's expansion.

Contribution

It provides a detailed semiclassical analysis of quantum effects on phantom-energy singularities, highlighting the differential impact of scalar, spinor, and vector fields.

Findings

Scalar and spinor vacuum states strengthen the singularity.

Vector vacuum states weaken the singularity.

Quantum effects can modify the universe's accelerating expansion near singularities.

Abstract

This paper is committed to calculations near a type of future singularity driven by phantom energy. At the singularities considered, the scale factor remains finite but its derivative diverges. The general behavior of barotropic phantom energy producing this singularity is calculated under the assumption that near the singularity such fluid is the dominant contributor. We use the semiclassical formula for renormalized stress tensors of conformally invariant fields in conformally flat spacetimes and analyze the softening/enhancing of the singularity due to quantum vacuum contributions. This dynamical analysis is then compared to results from thermodynamical considerations. In both cases, the vacuum states of quantized scalar and spinor fields strengthen the accelerating expansion near the singularity whereas the vacuum states of vector fields weaken it.