Comment on "Non-vacuum conformally flat space-times: dark energy"

TL;DR

This paper critiques a class of Einstein solutions with negative pressure, clarifying the nature of the stress tensor and the physical interpretation of a key constant, challenging previous assumptions.

Contribution

It demonstrates that the stress tensor is anisotropic and reinterprets the constant as related to Rindler acceleration rather than mass.

Findings

Stress tensor is anisotropic

Equation of state parameter differs from -1/2

Constant relates to Rindler acceleration

Abstract

Ibohal, Ishwarchandra and Singh proposed a class of exact, non-vacuum and conformally flat solutions of Einstein's equations whose stress tensor $T_{ab}$ has negative pressure. We show that $T_{ab}$ corresponds to an anisotropic fluid and the equation of state parameter seems not to be $\omega = -1/2$. We consider the authors' constant cannot be the mass of a test particle but is related to a Rindler acceleration of a spherical distribution of uniformly accelerating observers.