Kantowski-Sachs universes sourced by a Skyrme fluid

Parisi, Luca; Radicella, Ninfa; Vilasi, G.

doi:10.1103/physrevd.91.063533

Cited by 30 publications

(21 citation statements)

References 52 publications

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“…While the stability of the Skyrme black hole is already established [36] the stability of other hairy black holes is not fully understood yet [37] (see also [38,39]). Cosmological applications of the Skyrme model have also been considered [40,41].…”

Section: Introductionmentioning

confidence: 99%

Bianchi IX cosmologies in the Einstein-Skyrme system in a sector with nontrivial topological charge

et al. 2019

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The dynamics of the most general Bianchi IX cosmology with three time dependent scale factors for the Einstein-Skyrme system is analyzed. For the Skyrmion, a generalized hedgehog ansatz with unit baryon charge is introduced. The most remarkable feature of this ansatz is that, in the above topologically non-trivial sector with unit topological charge, the Skyrme field equations are identically satisfied on any Bianchi IX metric. We will show that due to this feature the complete set of coupled Einstein-Skyrme field equations can be deduced from a suitable minisuperspace Lagrangian. The latter allows to perform a systematic study of the integrability properties of the Einstein-Skyrme system for the Bianchi IX cosmology. Moreover, some analytic and algebraic solutions for the Einstein-Skyrme model are derived. Another remarkable consequence of the present formalism is that it is possible to derive the Wheeler de-Witt equation for the Bianchi IX metric in the Einstein-Skyrme cosmology in which all the effects of the Skyrmion are encoded in an effective potential of the minisuperspace Lagrangian.

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Section: Introductionmentioning

confidence: 99%

Bianchi IX cosmologies in the Einstein-Skyrme system in a sector with nontrivial topological charge

et al. 2019

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“…Regular particle-like configurations [22] and dynamical properties of the system have also been investigated numerically [23]. Even in the sector with vanishing topological charge the cosmological consequences of the Skyrme model are quite interesting [24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Cosmological Einstein-Skyrme solutions with nonvanishing topological charge

Canfora¹,

Paliathanasis²,

Taves³

et al. 2017

Phys. Rev. D

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Time-dependent analytic solutions of the Einstein-Skyrme system -gravitating Skyrmions-, with topological charge one are analyzed in detail. In particular, the question of whether these Skyrmions reach a spherically symmetric configuration for t → +∞ is discussed. It is shown that there is a static, spherically symmetric solution described by the Ermakov-Pinney system, which is fully integrable by algebraic methods. For Λ > 0 this spherically symmetric solution is found to be in a "neutral equilibrium" under small deformations, in the sense that under a small squashing it would neither blow up nor dissapear after a long time, but it would remain finite forever (plastic deformation). Thus, in a sense, the coupling with Einstein gravity spontaneously breaks the spherical symmetry of the solution. However, in spite of the lack of isotropy, for t → ∞ (and Λ > 0) the space time is locally flat and the anisotropy of the Skyrmion only reflects the squashing of spacetime.

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“…We give some examples of those works in Refs. [7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22]. Even if the gravitational theory is not general relativity, we may find several works where the cosmological models have a KS spacetime.…”

Section: Introductionmentioning

confidence: 99%

An anisotropic Kantowski-Sachs universe with radiation, dust and a phantom fluid

Oliveira-Neto,

Canedo,

Monerat

2021

Preprint

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In the present work, we study the dynamical evolution of an homogeneous and anisotropic KS cosmological model, considering general relativity as the gravitational theory, such that there are three different perfect fluids in the matter sector. They are radiation, dust and phantom fluid. Our main motivation is determining if the present model tends to an homogeneous and isotropic FRW model, during its evolution. Also, we want to establish how the parameters and initial conditions of the model, quantitatively, influence the isotropization of the present model. In order to simplify our task, we use the Misner parametrization of the KS metric. In terms of that parametrization the KS metric has two metric functions: the scale factor a(t) and β(t), which measures the spatial anisotropy of the model. We solve, numerically, the Einstein's equations of the model and find a solution where the universe starts to expand from a, small, initial size and continues to expand until it ends in a Big Rip singularity. We explicitly show that for the expansive solution, after same time, the universe becomes isotropic. Based on that result, we can speculate that the expansive solution may represent an initial, anisotropic, stage of our Universe, that later, due to the expansion, became isotropic.

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Kantowski-Sachs universes sourced by a Skyrme fluid

Cited by 30 publications

References 52 publications

Bianchi IX cosmologies in the Einstein-Skyrme system in a sector with nontrivial topological charge

Bianchi IX cosmologies in the Einstein-Skyrme system in a sector with nontrivial topological charge

Cosmological Einstein-Skyrme solutions with nonvanishing topological charge

An anisotropic Kantowski-Sachs universe with radiation, dust and a phantom fluid

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