Note on Tsallis holographic dark energy in Brans-Dicke cosmology

TL;DR

This paper examines the validity of power law variation of the Brans-Dicke scalar field in a universe with Tsallis holographic dark energy, finding it only consistent under specific parameter choices and noting the violation of energy conservation.

Contribution

It identifies conditions under which the power law variation of the scalar field is valid and highlights the non-conservation of energy in this model.

Findings

Power law variation of scalar field is valid only for specific parameters.

Energy conservation law does not hold for Tsallis holographic dark energy in this context.

Certain parameter choices lead to consistent physical descriptions of the universe.

Abstract

In this comment, we have investigated that the power law variation of Brans-Dicke scalar field $(\phi)$ with scale factor $(a)$ is not validated by field equations in general for the Universe filled with dark matter and Tsallis type holographic dark energy. However, for specific choice of free parameters $(\omega = -\frac{3}{2}\;\; \&\;\; n = -1)$ which are differ from its values fixed in Ghaffari et al \textcolor{blue}{[Ghaffari et al. Euro. Phys. J. C \textbf{78}, 706 (2018)]} to describe various physical properties of the Universe in derived model, the power law variation of $\phi$ with $a$ leads to consistent results. Further, we notice that the energy conservation law for Tsallis holographic dark energy in Brans-Dicke gravity does not hold.