Comment on "Szekeres universes with homogeneous scalar fields"

Abstract

Two recently published papers (J.D. Barrow and A. Paliathanasis, Eur. Phys. J. C. (2018, 2019)) claim to have found exact solutions of Einstein's field equations belonging to the class of non-trivial Szekeres models, whose source is a mixture of dust and a homogeneous time-dependent scalar field, where the energy-momentum tensors of both mixture components are independently conserved. We prove that the independent conservation of these two mixture components necessarily leads to solutions belonging to the set of spatially homogeneous subcases of the Szekeres family: Friedmann-Lemaître-Robertson-Walker for class I, and Kantowski-Sachs, Bianchi-Behr I or Bianchi-Behr $\mbox{VI}_{\tiny{\mbox{-1}}}$ for class II.

arXiv comment2 pages. Comment on "Szekeres universes with homogeneous scalar fields" and "Cyclic Szekeres universes" by Barrow and Paliathanasis, Eur. Phys. J. C. (2018, 2019); arXiv:1808.00173 and arXiv:1901.09173

References in corpus (6)

• Interactions in Scalar Field Cosmology
• Szekeres Universes with Homogeneous Scalar Fields
• Inhomogeneous models of interacting dark matter and dark energy
• Lagrangian theory of structure formation in relativistic cosmology. VI. Comparison with Szekeres exact solutions
• Cyclic Szekeres Universes
• Pancakes as opposed to Swiss Cheese

Cited by in corpus (2)

• On general-relativistic Lagrangian perturbation theory and its non-perturbative generalization
• Beyond relativistic Lagrangian perturbation theory. I. An exact-solution controlled model for structure formation