Cyclic Szekeres universes

Barrow, John D.; Paliathanasis, Andronikos

doi:10.1140/epjc/s10052-019-6890-5

Cited by 11 publications

(15 citation statements)

References 35 publications

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“…The cosmological constant term was introduced by Barrow et al [23] where the inhomogeneous analogue of the CDM model was derived. Other kinds of matter source have been introduced, such as heat flow, electromagnetic field, viscosity, and an aether field in the context of Einstein-aether theory [24][25][26][27][28][29][30][31].…”

Section: Introductionmentioning

confidence: 99%

Inhomogeneous spacetimes in Weyl integrable geometry with matter source

2020

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We investigate the existence of inhomogeneous exact solutions in Weyl Integrable theory with a matter source. In particular, we consider the existence of a dust fluid source while for the underlying geometry we assume a line element which belongs to the family of silent universes. We solve explicitly the field equations and we find the Szekeres spacetimes in Weyl Integrable theory. We show that only the isotropic family can describe inhomogeneous solutions where the LTB spacetimes are included. A detailed analysis of the dynamics of the field equations is given where the past and future attractors are determined. It is interesting that the Kasner spacetimes can be seen as past attractors for the gravitation models, while the unique future attractor describes the Milne universe similar with the behaviour of the gravitational model in the case of General Relativity.

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Section: Introductionmentioning

confidence: 99%

Inhomogeneous spacetimes in Weyl integrable geometry with matter source

2020

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“…The resulting spacetime is inhomogeneous but the scale factor Φ (t) does not depend on the space variable x. These kinds of spacetimes have been determined before in the case of GR with a homogeneous scalar field [61], or with an isotropic ideal gas [62].…”

Section: Subclass B (Ii)mentioning

confidence: 99%

“…We continue by determining the critical points of the dynamical system (60)- (62) and study the physical properties on the solution at the critical points as also the stability. In order to compare the results of Einstein-aether gravity with that of GR, let us proceed with the stability analysis of the Szekeres-Szafron [51].…”

Section: Dynamical Evolutionmentioning

confidence: 99%

“…For c 1 = c 2 = 0, the dynamical system (60)- (62) reduces to that of the Szekeres-Szafron system. Every critical point P = (Ω m (P ) , Σ (P ) , ǫ (P )) is a solution of the following algebraic system F 1 (Ω m , Σ, ǫ; γ, 0, 0) = 0 , F 2 (Ω m , Σ, ǫ; γ, 0, 0) = 0, F 3 (Ω m , Σ, ǫ; γ, 0, 0) = 0.…”

Section: Stability Analysis For the Szekeres-szafron System In Grmentioning

confidence: 99%

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Inhomogeneous spacetimes in Einstein-æther cosmology

Paliathanasis¹

2020

Class. Quantum Grav.

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We investigate the existence of inhomogeneous Szekeres spacetimes in Einstein-aether theory. We show that inhomogeneous solutions which can be seen as extension of the Szekeres solutions existing in Einstein-aether gravity only for a specific relation between the dimensionless coefficients which defines the coupling between the aether filed with gravity. The two Szekeres classes of solutions are derived. Also a class of inhomogeneous FLRW-like spacetimes is allowed by the theory for arbitrary values of the dimensionless coefficients of the aether field. The stability of the solutions obtained is performed from where we find that the field equations evolve more variously in Einstein-aether than in General Relativity, where isotropic spacetimes and Kantowski-Sachs spacetimes are found to be attractors.

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“…In two recently published articles, Paliathanasis (2018, 2019) [1,2] claim to have found exact solutions of Einstein's field equations belonging to the class of non-trivial (i.e., spatially inhomogeneous) Szekeres models, whose source is a mixture of dust and a homogeneous time-dependent scalar field, where the energy-momentum tensors (EMTs) of both mixture components are independently conserved. We prove in the present comment that these solutions are inconsistent with the authors' assumptions, as independent conservation of these two mixture components necessarily leads to their solutions belonging to the set of spatially homogeneous subcases of the Szekeres family: Friedmann-Lemaître-Robertson-Walker (FLRW) for class I, and Kantowski-Sachs (KS), Bianchi (or Bianchi-Behr-Schücking) I or Bianchi VI −1 for class II.…”

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confidence: 99%