Cosmological dynamics of tachyonic teleparallel dark energy

TL;DR

This paper analyzes the cosmological behavior of a tachyonic scalar field non-minimally coupled to gravity within teleparallel gravity, revealing a new matter-dominated era influenced by the non-minimal coupling.

Contribution

It introduces a dynamical analysis of tachyonic teleparallel dark energy with a variable coupling, highlighting a novel matter-dominated era not present in canonical scalar field models.

Findings

Existence of a field-matter-dominated era ($$MDE) influenced by the non-minimal coupling.

The universe can have a significant portion of energy density from the tachyon field during matter domination.

The model differs from canonical scalar field scenarios by allowing a dynamically changing coupling coefficient.

Abstract

A detailed dynamical analysis of the tachyonic teleparallel dark energy model, in which a non-canonical scalar field (tachyon field) is non-minimally coupled to gravitation, is performed. It is found that, when the non-minimal coupling is ruled by a dynamically changing coefficient $\alpha\equiv f_{,\phi}/\sqrt{f}$, with $f(\phi)$ an arbitrary function of the scalar field $\phi$, the universe may experience a field-matter-dominated era "$\phi$MDE", in which it has some portions of the energy density of $\phi$ in the matter dominated era. This is the most significant difference in relation to the so-called teleparallel dark energy scenario, in which a canonical scalar field (quintessence) is non-minimally coupled to gravitation.