Stealth's cosmologies

TL;DR

This paper introduces a new class of cosmological models featuring stealth scalar fields that, despite not back-reacting on spacetime, influence cosmological dynamics and can be quantitatively analyzed.

Contribution

It presents a novel method to incorporate stealth scalar fields into cosmological models with explicit expressions for their contributions.

Findings

Stealth fields contribute to cosmological energy density and pressure.

Analytic expressions for stealth contributions are derived.

Behavior of self-interaction potentials is analyzed.

Abstract

We present a novel approach to construct cosmological models endowed with a particular scalar field, the stealth. The model is constructed by studying a scalar field no-minimally coupled to the gravitational field with sources; as sources, we used a perfect fluid and analyzed the simplest case of dust and the power-law cosmology. Surprisingly, we find that these stealth fields, which have no back-reaction to background space-time, have a contribution to cosmological dynamics. Furthermore, we provide analytic expressions of the stealth's contributions to the energy density in both cases, and for the pressure in the power-low cosmology, which means that such contributions to cosmological evolution are quantifiable. Additionally, we discuss the behaviors of the self-interaction potential for some cases.